Re: Is this IBM keyboard compatible with the IBM 3279?
Den ons 4 mars 2020 kl 02:05 skrev Matt Burke via cctalk < cctalk@classiccmp.org>: > On 03/03/2020 16:48, Mattis Lind via cctalk wrote: > > The connector is the correct one. It has four jumpers that could be used > > for setting one of the keyboard types using the KB ident lines. > > > > https://i.imgur.com/PhfvKaV.jpg > > > > https://i.imgur.com/VPT38cK.jpg > > > > https://i.imgur.com/nN1gtFu.jpg > > > > Which terminal was it used for originally? > > > > /Mattis > > It looks a lot like the keyboard for a 3178 except that has a DA15 > connector and there is a blue switch on the top to select between upper > and mixed case. > Yes, it indeed looks a 3178 kb. But as you said that one had a 15 pin dsub. This 25 dsub actually has the missing pins in the righty places compared to the 3279 so I am leaning towards that it in fact is a 3279 compatible keyboard. Will probably trace the lines and compare those with the 3279 KB connector to see if at least ident pins and power pins is in the right places. Then I will just go ahead and try to connect it to the 3279 and see what happens when executing the keyboard test (test 2) of the 3279. /Mattis > > Matt >
Re: For those with 6809 experience
My assumption is, that the LDA address access is too late at the end of the instruction cycle, and the CPU already started the next instruction cycle internally. HALT will be acknowledged only during the instruction cycle following the LDA. It would be interesting to measure, when the LDA pulls down the HALT compared to the last instruction cycle signal (LIC). Maybe using LDD will work better, because the HALT signal will be asserted one clock before the instruction cycle ends. Thomas Am 29.02.2020 um 23:42 schrieb Jim Brain via cctalk: Looking at the datasheet for the 6809 (specifically, the 6809E that needs incoming quadrature clock), I read that !HALT can be asserted 200nS (for 1MHz part) before falling Q and the CPU will finish the existing instruction and then go into a HALT state as long as the HALT line is low during the falling edge of Q. That's the store from the datasheet, but when I am testing it, I see that, even if I pull HALT low at the very beginning of the last cycle of an instruction, the 6809 will not acknowledge the HALT until executing the next instruction. My logic is watching for IO address $ff61. When found, it drops Q so, to start the HALT condition, I need only: lda $ff61 Not that the trigger is being performed by the code, so the current instruction (the lda) should complete and then the CPU should go into HiZ. What I see is: lda $ff61 lda $ff60 <- the next instruction executed, and THEN the CPU goes into HiZ. I can deal with this (Yes, I should just look at BS=BA=1, which tell when to safely use the bus, but I don't have access to those signals for this project), but I thought I'd see if this was known by all, or if there is something I am missing. Jim
RE: Good picture of a S360.
For those interested there are several 360/67 pictures here... http://history.cs.ncl.ac.uk/anniversaries/40th/images/ibm360_672/index.html and one of the 360/40 console at MOTAT, Auckland, New Zealand here:- https://1drv.ms/u/s!Ag4BJfE5B3onlq0VBQd65MgE8EH67g?e=1DiSyI Dave > -Original Message- > From: cctalk On Behalf Of Chris Zach via > cctalk > Sent: 04 March 2020 03:25 > To: CCTalk mailing list > Subject: Good picture of a S360. > > From Imgur. The question: How the heck can you wear stiletto heels in a > data center? > > https://i.imgur.com/rakM62J.jpg
Re: Good picture of a S360.
Marc reckoned > Yeah, a 360/50. When all the tapes are organized and color matched to the > computer, you know it’s just a photo-op of a fake data center, or at best a > real one with many hours of preparation for a beauty shot. Nice picture > though! It could be the 'white room'. This was a windowless machine room IBM set up for marketing and product photography of their systems in the 1960s. I think it was located in NY. There was only a paragraph or two about the white room in (IIRC) the book 'The Interface: IBM and the Transformation of Corporate Design' by John Harwood. There happened to be a copy in the Uni of Queensland bookshop a couple years ago. I spotted it on the shelf and thumbed through it at the time, but it had so little on what interested me (and I suspect cctalk readers) relative to the cost I didn't buy it so I'm only going on memory here. Steve.
Re: Good picture of a S360.
Yeah, a 360/50. When all the tapes are organized and color matched to the computer, you know it’s just a photo-op of a fake data center, or at best a real one with many hours of preparation for a beauty shot. Nice picture though! Marc > On Mar 3, 2020, at 8:13 PM, Zane Healy via cctalk > wrote: > > > >> On Mar 3, 2020, at 7:33 PM, Chuck Guzis via cctalk >> wrote: >> >>> On 3/3/20 7:24 PM, Chris Zach via cctalk wrote: >>> From Imgur. The question: How the heck can you wear stiletto heels in a >>> data center? >>> >>> https://i.imgur.com/rakM62J.jpg >> >> Marketing models. Too clean. > > At least I finally know what the tapes that went in those cases looked like. > :-) I have at least a couple of the cases that came out of Tektronix 40+ > years ago. > > Zane > > >
Re: Good picture of a S360.
ETA: I believe that the CPU shown is a 360/50. --Chuck
Re: Good picture of a S360.
On 3/3/20 8:12 PM, Zane Healy wrote: > At least I finally know what the tapes that went in those cases looked like. > :-) I have at least a couple of the cases that came out of Tektronix 40+ > years ago. Every manufacturer had their own version of the hard tape cases. 3M, for exmaple, used a rubber "boot" in the center of the case that expanded when a "plug" was depressed. Squeeze tabs/push buttons in the center were also used. Sad that most of the hard cases were junked when the "Wright Line" hanging strips came in. --Chuck
Re: Good picture of a S360.
> On Mar 3, 2020, at 7:33 PM, Chuck Guzis via cctalk > wrote: > > On 3/3/20 7:24 PM, Chris Zach via cctalk wrote: >> From Imgur. The question: How the heck can you wear stiletto heels in a >> data center? >> >> https://i.imgur.com/rakM62J.jpg > > Marketing models. Too clean. At least I finally know what the tapes that went in those cases looked like. :-) I have at least a couple of the cases that came out of Tektronix 40+ years ago. Zane
Re: Good picture of a S360.
On 3/3/20 7:24 PM, Chris Zach via cctalk wrote: > From Imgur. The question: How the heck can you wear stiletto heels in a > data center? > > https://i.imgur.com/rakM62J.jpg Marketing models. Too clean.
Re: Mystery 1970 core board
On 2020-Mar-03, at 4:18 PM, Jules Richardson via cctalk wrote: > Hopefully collective wisdom can help on this one - does anyone have a clue > what system this core board was from: > http://www.classiccmp.org/acornia/tmp/coresmall.jpg > > The curved edge connectors (presumably to make board insertion easier) are > quite distinctive, plus the way the power's fed in via an edge connector on > the "far" side of the board. What's interesting to me is the core ring size; > the TTL ICs on the board have 1970 date codes, but I didn't think that the > rings got quite that small until right at the end of core's era, more toward > the end of the decade. > > It seems to be 8 blocks of 64x64, i.e. 4KB. p/n on the main board of > 2001000755, and just hidden from view under the core daughterboard is a logo > that says "LEC", which I suppose might be meaningful. > > There's a bigger (2181x1863) image as "coreboard.jpg" in the same dir if more > detail helps (I doubt it), but it's 2.4MB so maybe save Jay's bandwidth by > only looking at that one if you absolutely have to :-) Can't help with the system of origin, but a little observational analysis: It looks to be 16 bits wide rather than 8, I think you'll find there's another 8 bit-arrays of cores on the underside of the planar-array daughter board. The little upside-down module boards along the top would be the sense amplifiers, the circuitry along the right would be drivers for one end of the address lines for one axis. Unfortunately, it doesn't appear to be a complete module. It looks like the inhibit drivers and 3/4 of the address drivers would have been on another board.
Good picture of a S360.
From Imgur. The question: How the heck can you wear stiletto heels in a data center? https://i.imgur.com/rakM62J.jpg
Re: Is this IBM keyboard compatible with the IBM 3279?
On 03/03/2020 16:48, Mattis Lind via cctalk wrote: > The connector is the correct one. It has four jumpers that could be used > for setting one of the keyboard types using the KB ident lines. > > https://i.imgur.com/PhfvKaV.jpg > > https://i.imgur.com/VPT38cK.jpg > > https://i.imgur.com/nN1gtFu.jpg > > Which terminal was it used for originally? > > /Mattis It looks a lot like the keyboard for a 3178 except that has a DA15 connector and there is a blue switch on the top to select between upper and mixed case. Matt
Re: Wang 2200 Diskettes
On 3/3/20 4:26 PM, Joe George wrote: > > Yup! Single sided, single density, 32 hard sectors. And the Wang 2200 had > apparently some weird insert orientation, the “Wang” labels are on the back > of the diskettes, opposite side of the manufacturer sticker. > > Cheers, My recollection is that the 8" floppy drives (in a lowboy floor-standing unit) were vertically mounted and placed to the right of the operator. The floppy eject button was then closest to the operator and any disk inserted would be visible from the "rear" of the floppy. Not nearly as weird as the Altos ACS8000, for example, that mounted the floppy drives upside-down and horizontally, such that the eject button was topmost. Those disks do have content labels placed on what we'd consider the "backside" of the floppy for obvious reasons. Did any 5.25" floppy-equipped systems do this? --Chuck
Mystery 1970 core board
Hopefully collective wisdom can help on this one - does anyone have a clue what system this core board was from: http://www.classiccmp.org/acornia/tmp/coresmall.jpg The curved edge connectors (presumably to make board insertion easier) are quite distinctive, plus the way the power's fed in via an edge connector on the "far" side of the board. What's interesting to me is the core ring size; the TTL ICs on the board have 1970 date codes, but I didn't think that the rings got quite that small until right at the end of core's era, more toward the end of the decade. It seems to be 8 blocks of 64x64, i.e. 4KB. p/n on the main board of 2001000755, and just hidden from view under the core daughterboard is a logo that says "LEC", which I suppose might be meaningful. There's a bigger (2181x1863) image as "coreboard.jpg" in the same dir if more detail helps (I doubt it), but it's 2.4MB so maybe save Jay's bandwidth by only looking at that one if you absolutely have to :-) thanks, Jules
Re: Is this IBM keyboard compatible with the IBM 3279?
I was doing field service on 3270 terminals among other things up until 1983 and I never saw a 3278 or 3279 with a keyboard like this, all the ones I recall seeing where an earlier capacitive switch keyboard that is sometimes referred to as the "Beam-spring" switch. That said this ones does seem to have all the right keys in the right place for a 3270 keyboard. The replacement product for the 3279 was announced spring of 1984 so 3279 may have already been out of production when this keyboard was made. Paul. On 2020-03-03 12:48 p.m., Mattis Lind via cctalk wrote: The connector is the correct one. It has four jumpers that could be used for setting one of the keyboard types using the KB ident lines. https://i.imgur.com/PhfvKaV.jpg https://i.imgur.com/VPT38cK.jpg https://i.imgur.com/nN1gtFu.jpg Which terminal was it used for originally? /Mattis
Re: What is this System 360 peripheral/maintenance console?
Here's my contribution to this topic: https://drive.google.com/open?id=1iidmMNXV3arCqlMmJdzWNFwgtrjDjpt6 Our national broadcasting company visited my unofficial museum and filmed my computer collection for the documentary "Lada, Laika, Marx ja mä". You can see there the 1800 running a simple program. More photos of the 1800 is in my blog. - Johannes Thelen Finland Before microcomputers blog (Finnish) http://ennenmikrotietokoneita.blogspot.fi/ From: cctalk on behalf of Steve Malikoff via cctalk Sent: Tuesday, March 3, 2020 12:40 PM To: General Discussion: On-Topic and Off-Topic Posts Subject: Re: What is this System 360 peripheral/maintenance console? > On Mon, Mar 2, 2020 at 10:51 AM Chuck Guzis via cctalk < >> Will's right - the 16-bit register display should have been a tipoff. >> >> See http://www.dvq.com/1800/1800.htm for lots of images. >> 1800->industrial control version of the 1130. >> >> --Chuck >> > Thank you, I will update how I have it documented on the web site. I have > a lot of 1800 docs, maybe I can find the actual hardware there. > Bill Thanks everyone. I saw the 360 black and chrome knobs and black tipped switches and started searching '360' things, hence the question. Steve.
Re: stuff for sale - recent move
> > On Sun, 1 Mar 2020 at 17:58, Joseph Zatarski via cctalk > wrote: > > > > I've started inventorying a lot of the stuff I'd like to pass on here: > > > https://docs.google.com/spreadsheets/d/19vhF-o6vx9g7l-D8cvLJ5OPJzpdmU9PTTknbxY-mY58/edit?usp=sharing > > I can't see these in the Google sheet, for some reason: > > > -Mac network cards (nubus and one for IIsi or SE/30) as well as a couple > > other accessories (Dayna Mini Etherprint, AAUI transceiver, more > > accessories to come) > > I am interested in an SE/30 NIC and associated bits (transciever, > AppleTalk bridge). > > I am happy to pay international postage. I'm in Prague. > -- > Liam Proven ? Profile: https://about.me/liamproven > Email: lpro...@cix.co.uk ? gMail/gTalk/gHangouts: lpro...@gmail.com > Twitter/Facebook/LinkedIn/Flickr: lproven ? Skype: liamproven > UK: +44 7939-087884 ? ?R (+ WhatsApp/Telegram/Signal): +420 702 829 053 Hello Liam, The NICs I have are Asante brand. They are located in the Apple/Macintosh category. https://docs.google.com/spreadsheets/d/19vhF-o6vx9g7l-D8cvLJ5OPJzpdmU9PTTknbxY-mY58/edit#gid=1065383164=B3 Unfortunately for you, sale is pending on the SE/30 NIC. If the sale falls through, you are in line behind one other person. I'm fairly confident that even if the first buyer falls through, the second in line will not. If you're still interested in the other accessories, I can have a look when I get home, get a few pictures put up for you, and we can continue from there. International shipping should not be an issue, filling out a customs form is not very hard. Best Regards, Joe Zatarski
TOPS-20 networking
*TOPS-20*
The set of config files you need to edit in TOPS-20 is found here, about
halfway down the page:
http://www.ldx.ca/notes/tops-20-notes.html
I'll paste it here:
Configuring the system
The *Panda Distribution* README has this to say about initial configuration:
You’ll need to edit the following files. EMACS is installed on this system,
along with TECO and EDIT. [More on these editors later.]
SYSTEM:7-1-CONFIG.CMD to set your timezone
SYSTEM:HOSTS.TXT to define your local host name and network
SYSTEM:INTERNET.ADDRESS to define (again!) your IP address – must be the
same as in klt20.ini. Also define your netmask here as LOGICAL-HOST-MASK
SYSTEM:INTERNET.GATEWAYS to define your IP gateway
SYSTEM:INTERNET.NAMESERVERS Don’t bother with SYSTEM:INTERNET.NAMESERVERS.
That is the configuration file for DEC’s resolver; although it’s simpler it
has some interoperability problems with MMAILR which haven’t been resolved
yet.
SYSTEM:MONNAM.TXT to define your system name
DOMAIN:RESOLV.CONFIG to define your DNS servers, your default domain
(replacing MYDOMAIN.COM) and any users in addition to OPERATOR who can send
control messages to the resolver.
To actually edit any of those, you'll probably need to ENABLE first, eg:
@ena
$
The dollar-sign ($) prompt indicates that your privileges are enabled.
*Linux Host*
On the host side, I like to convert my ethernet to a bridge so I can add
virtual interfaces easily. Here's the script I use (requires sudo, and
that the user running it be in group adm, and that the tuntap devices be
owned by and writeable by group adm):
#!/bin/sh
eth0text=$(/sbin/ifconfig eth0 | grep "inet ")
HOSTIP=$(echo "${eth0text}" | awk '{print $2}')
HOSTNETMASK=$(echo "${eth0text}" | awk '{print $4}')
HOSTBCASTADDR=$(echo "${eth0text}" | awk '{print $6}')
HOSTDEFAULTGATEWAY=$(/sbin/route -n | grep ^0.0.0.0 | awk '{ print $2 }')
# Change as we add more guest OSes with network stacks
_maxtap=2
#
for i in $(seq 0 ${_maxtap}); do
/usr/bin/tunctl -t tap${i} -u adam -g adm
/sbin/ifconfig tap${i} up
done
#
# Now convert eth0 to a bridge and bridge it with the TAP interfaces
/sbin/brctl addbr bridge0
sleep 1
/sbin/brctl addif bridge0 eth0
sleep 1
/sbin/brctl setfd bridge0 0
/sbin/ifconfig eth0 0.0.0.0
/sbin/ifconfig bridge0 $HOSTIP netmask $HOSTNETMASK broadcast
$HOSTBCASTADDR up
# set the default route to the bridge0 interface
/sbin/route add -net 0.0.0.0/0 gw $HOSTDEFAULTGATEWAY
#
# bridge in the tap devices
for i in $(seq 0 ${_maxtap}); do
/sbin/brctl addif bridge0 tap${i}
/sbin/ifconfig tap${i} 0.0.0.0
done
For some reason this seems to work even though that should be group
netdev. I guess because "adam," who is running the emulator, owns the
tun/tap devices.
I have this in /etc/udev/rules.d/99_net_tun.rules:
KERNEL=="tun", GROUP="netdev", MODE="0660", OPTIONS+="static_node=net/tun"
I don't think that's standard; I think I added that at some point.
And then in klt20.ini, I have a statement that looks like:
devdef ni0 564 ni20 ifc=bridge0 ipaddr=192.168.248.249 dedic=false
And then finally the dnpni20 executable is setuid root.
All of this together gives me a TCP/IP stack on klh10 that allows the
emulator to run as me, not as root, and bridges the TOPS-20 host into my
real network.
Adam
Re: Is this IBM keyboard compatible with the IBM 3279?
On 3/3/20 8:48 AM, Mattis Lind via cctalk wrote: > Which terminal was it used for originally? IC date codes appear to be 1983/84
Is this IBM keyboard compatible with the IBM 3279?
The connector is the correct one. It has four jumpers that could be used for setting one of the keyboard types using the KB ident lines. https://i.imgur.com/PhfvKaV.jpg https://i.imgur.com/VPT38cK.jpg https://i.imgur.com/nN1gtFu.jpg Which terminal was it used for originally? /Mattis
Re: For those with 6809 experience
On 3/3/2020 2:26 AM, Veit, Holger via cctalk wrote: Am 01.03.2020 um 00:42 schrieb Jim Brain via cctalk: What are you trying to accomplish? Right now, I am just trying to understand how one pulls the 6809 off the system bus and get some more experience in performing DMA activities. I have no specific end goal in mind. I guess you are using $FF61 as a trigger to start a DMA transfer, or alike. I've seen something like this in code already, so it might have been be known in developer circles for long. The plain simple fix apparently was to add one or two NOPs after the initiating address reference. The hardware price could be an additional flipflop and another comparator. Detecting $FF61 wil arm the FF and a following NOP on databus will initiate the operation. If no NOP follows, the FF is reset.However, the latter situation should not occur when all instances of LDA $FF61 are properly followed by NOP. My first attempt was to simply hold off the DMA activity for a few cycles, which indeed worked. When I hooked up the logic analyzer, I determined that no matter how early in the last cycle I pulled !HALT low, the CPU would execute one more instruction before acting on the HALT condition. I then put, as you note, a NOP in my code and could see that it was being executed after the access to $ff61, following which the BA/BS lines would go high and the Address bus went to $, as expected. At that point, someone pointed me to a small notation on the 6809E datasheet on the timing diagram showing the HALT usage. It creates more questions, but it did answer this one. Thus, in case it is of any help to others (unlikely, given the age of the CPU), even though the text in the datasheet does not mention this constraint (I know, completely unexpected :-), the timing diagram points out that the HALT condition (and interrupt conditions as well) must occur tPCS ns before the falling edge of Q in the *second* to last cycle of the current instruction in order to be acknowledged. I noticed the text on the datasheet when looking at the timing, but assumed they presented the HALT condition on the second to last cycle as a way to illustrating to the designers that the system would not immediately go into a HALT state, but would indeed (and the text confirms this) complete the current instruction. I have no idea why the extra cycle is needed (I assume internal pipelining), but I can confirm the IC does indeed behave in the above manner. The person who pointed me to the datasheet also (out of curiosity) ran a test to see if interrupts or the HALT condition take precedence if both arrive at the same time, and it appears HALT takes precedence (more testing is needed there, though) I appreciate your note. It's been an interesting exploration of the CPU. Jim -- Jim Brain br...@jbrain.com www.jbrain.com
Re: stuff for sale - recent move
On Sun, 1 Mar 2020 at 17:58, Joseph Zatarski via cctalk wrote: > > I've started inventorying a lot of the stuff I'd like to pass on here: > https://docs.google.com/spreadsheets/d/19vhF-o6vx9g7l-D8cvLJ5OPJzpdmU9PTTknbxY-mY58/edit?usp=sharing I can't see these in the Google sheet, for some reason: > -Mac network cards (nubus and one for IIsi or SE/30) as well as a couple > other accessories (Dayna Mini Etherprint, AAUI transceiver, more > accessories to come) I am interested in an SE/30 NIC and associated bits (transciever, AppleTalk bridge). I am happy to pay international postage. I'm in Prague. -- Liam Proven – Profile: https://about.me/liamproven Email: lpro...@cix.co.uk – gMail/gTalk/gHangouts: lpro...@gmail.com Twitter/Facebook/LinkedIn/Flickr: lproven – Skype: liamproven UK: +44 7939-087884 – ČR (+ WhatsApp/Telegram/Signal): +420 702 829 053
Re: Panda TOPS20 networking trouble
what is the host environment? Linux? or something else? You have to set up some hoste networking, sometimes involving some installs of virtual networking bits. bb On Tue, Mar 3, 2020 at 12:25 AM David Griffith via cctalk wrote: > > > I'm having loads of trouble getting networking going with the Panda > Distribution of TOPS20 and KLH10. Could someone point me to a > step-by-step guide on doing this? > > > -- > David Griffith > d...@661.org > > A: Because it fouls the order in which people normally read text. > Q: Why is top-posting such a bad thing? > A: Top-posting. > Q: What is the most annoying thing in e-mail?
stuff for sale - recent move
Hi. I forgot to mention it’s an eye phone 11 PRO 256gb. I may be missing something -- *what's* an "eye phone"? I thought you were listing vintage kit, not smartphones? -- Liam Proven – Profile: https://about.me/liamproven Email: lproven at cix.co.uk – gMail/gTalk/gHangouts: lproven at gmail.com Twitter/Facebook/LinkedIn/Flickr: lproven – Skype: liamproven UK: +44 7939-087884 – ČR (+ WhatsApp/Telegram/Signal): +420 702 829 053 I believe Kevin replied to the wrong e-mail by mistake. He must be selling something himself and had a similar subject line. That said, no hits on my post yet? what, nobody needs nubus ethernet cards? or various ISA/PCI/PCI-X expansion cards? a dozen computer mice? DEC Alpha 4100 RAM? some nice combination SCSI/fastethernet cards? OK, I get that it's mostly junk ;), but no attention at all so far. Keep checking, getting more stuff in the list every day. I added a recent section so people can keep up on the recent additions without having to check the whole list. As before, I'm in the west suburbs of chicago in case anyone is local and sees some stuff they want.
Re: stuff for sale - recent move
On Tue, 3 Mar 2020 at 07:13, Kevin Lee via cctalk wrote: > > Hi. > > I forgot to mention it’s an eye phone > 11 PRO 256gb. I may be missing something -- *what's* an "eye phone"? I thought you were listing vintage kit, not smartphones? -- Liam Proven – Profile: https://about.me/liamproven Email: lpro...@cix.co.uk – gMail/gTalk/gHangouts: lpro...@gmail.com Twitter/Facebook/LinkedIn/Flickr: lproven – Skype: liamproven UK: +44 7939-087884 – ČR (+ WhatsApp/Telegram/Signal): +420 702 829 053
Re: What is this System 360 peripheral/maintenance console?
> On Mon, Mar 2, 2020 at 10:51 AM Chuck Guzis via cctalk < >> Will's right - the 16-bit register display should have been a tipoff. >> >> See http://www.dvq.com/1800/1800.htm for lots of images. >> 1800->industrial control version of the 1130. >> >> --Chuck >> > Thank you, I will update how I have it documented on the web site. I have > a lot of 1800 docs, maybe I can find the actual hardware there. > Bill Thanks everyone. I saw the 360 black and chrome knobs and black tipped switches and started searching '360' things, hence the question. Steve.
Re: For those with 6809 experience
Am 01.03.2020 um 00:42 schrieb Jim Brain via cctalk: Looking at the datasheet for the 6809 (specifically, the 6809E that needs incoming quadrature clock), I read that !HALT can be asserted 200nS (for 1MHz part) before falling Q and the CPU will finish the existing instruction and then go into a HALT state as long as the HALT line is low during the falling edge of Q. That's the store from the datasheet, but when I am testing it, I see that, even if I pull HALT low at the very beginning of the last cycle of an instruction, the 6809 will not acknowledge the HALT until executing the next instruction. My logic is watching for IO address $ff61. When found, it drops Q so, to start the HALT condition, I need only: lda $ff61 Not that the trigger is being performed by the code, so the current instruction (the lda) should complete and then the CPU should go into HiZ. What I see is: lda $ff61 lda $ff60 <- the next instruction executed, and THEN the CPU goes into HiZ. I can deal with this (Yes, I should just look at BS=BA=1, which tell when to safely use the bus, but I don't have access to those signals for this project), but I thought I'd see if this was known by all, or if there is something I am missing. Jim What are you trying to accomplish? I guess you are using $FF61 as a trigger to start a DMA transfer, or alike. I've seen something like this in code already, so it might have been be known in developer circles for long. The plain simple fix apparently was to add one or two NOPs after the initiating address reference. The hardware price could be an additional flipflop and another comparator. Detecting $FF61 wil arm the FF and a following NOP on databus will initiate the operation. If no NOP follows, the FF is reset.However, the latter situation should not occur when all instances of LDA $FF61 are properly followed by NOP. -- Holger
