Depending on the type of file you could do that in a limited way using the RS232 port; I did a rudimentary version to use 'records' in an 80K file. Slow.
On Thu, Nov 21, 2024 at 4:03 AM Alex ... <[email protected]> wrote: > If you're going to write your own (or heavily modify the) operating > system, i wonder if getting the filesystem out of RAM and onto a different > device would make more sense than expanding RAM without more address space. > > -Alex > > On Wed, Nov 20, 2024, 22:43 Mike Stein <[email protected]> wrote: > >> Unless you write your own operating system, *expanding* RAM linearly >> without bank switching is not "rare", it's not possible; the CPU can only >> address 64K, of which the lower 32K is occupied by the system ROM (OS, >> BASIC,other built-in apps) and a few K of RAM at the top are reserved for >> system variables. >> >> On Wed, Nov 20, 2024 at 9:36 PM Chris Kmiec <[email protected]> wrote: >> >>> Thanks everyone, looks like the LCD is what it is, and anything beyond >>> 32k RAM is very rare and not really worth it since REX can just switch out >>> the whole 32k. Time to dive in and start playing with what I have! >>> >>> Chris >>> >>> On Wed, Nov 20, 2024 at 4:18 PM Brian K. White <[email protected]> >>> wrote: >>> >>>> On 11/20/24 08:19, Chris Kmiec wrote: >>>> > >>>> > Hmm, I don’t see that feature in the specs for REX#. It has 1mb of >>>> Flash >>>> > memory for storing ROM images and can backup and restore the ram, but >>>> I >>>> > don’t see and RAM on REX that would allow me to max out Tandy’s >>>> onboard RAM. >>>> >>>> There's a few different things to explain here... >>>> >>>> The machine can only address up to 32k at a time, so in one sense there >>>> is no ram expansion beyond filling all 4 possible 8k sockets inside. >>>> You >>>> have a few different options for that. GGLabs sells a module called >>>> M10-RAM that you can buy. They have a site for the info but the actual >>>> buy link is on ebay or tindie etc. Otherwise you can build your own by >>>> following https://github.com/bkw777/Model_T_RAM >>>> >>>> (Apologies but this mail will end up having a few links to things from >>>> me on github since I've been playing with several forms of ram & rom >>>> addons for the 100-200 the last few years) >>>> >>>> There have been several forms of ram expansion that connect to the >>>> system bus and work by containing multiple banks of 32k and you have a >>>> software method to switch from one bank to another. You can only access >>>> the contents of a single bank at any one time. It's like unplugging all >>>> your chips and putting other chips in. I think the PG Design ones >>>> driver >>>> software might have some feature to be able to move a file from one >>>> bank >>>> to another, so there was some just barely form of access to the other >>>> banks. No one makes those currently but years ago Steve Adolf made >>>> something called QUAD which replicated the PG Design, and more recently >>>> I replicated & updated QUAD to make reQUAD >>>> https://github.com/bkw777/reQUAD >>>> No one makes it for sale but you can buy all the parts and build one >>>> yourself or find someone to do it for you. >>>> >>>> >>>> All 3 types of REX, (REX Classic, REX#, REXCPM) include a feature to do >>>> full backups & restore of the 32k internal ram. It's not quite the >>>> one-button instant swap like with the ram expansions, but just about. >>>> It's only a few presses to go into REXMGR and do a backup & then a >>>> restore. In fact I think he might have even streamlined that operation >>>> in the latest version for REX#. I know he did add some overwrite >>>> protection to avoid accidental deletes or overwrites. So in the end, >>>> it's functionally almost the same as having a ram expansion. It's just >>>> that underneath what's really happening is you are dumping the current >>>> ram out to a chunk of flash and then restoring some other chunk of >>>> flash >>>> over the ram. The actual ram expansions only gave you essentially the >>>> same outward functionality, just a little faster. >>>> >>>> REXCPM is a special case in that it also actually replaces your >>>> internal >>>> ram with it's own 32k. So if you have less than 32k, a REXCPM would >>>> give >>>> you 32k. >>>> >>>> If Steve can't sell you a REX# or REXCPM at the moment, there is an >>>> option to build your own REX Classic. >>>> https://github.com/bkw777/REX_Classic >>>> >>>> Not ram but probably the more practical way to have more room to work >>>> is >>>> disk space. The most practical answer for that is a Backpack. >>>> https://www.soigeneris.com/universal-backpack-drive >>>> >>>> I have something you can build called PDDuino which actually predates >>>> backpack, but backpack is far more feature rich and polished. (From >>>> what >>>> I can tell. I have not used one because since I want to work on the >>>> fully open source option that does the same thing, I don't want to ever >>>> be accused of even seeing the firmware in the backpack.) >>>> https://github.com/bkw777/PDDuino >>>> >>>> Basically the idea is 99% of the hardware is just an off-the-shelf >>>> Adafruit Feather or Teensy dev board and you just plug it in to a >>>> little >>>> serial port adapter board. It has a rechargeable lithium cell you >>>> recharge by usb, or you can just run on usb alone, or you can even run >>>> on power tapped from the BCR port. >>>> >>>> I've also made a version of a kind of ram disk that seems like at one >>>> time a few different people all made versions of essentially the same >>>> thing. It's a very neat little circuit where basically it's nothing but >>>> an address latch, a binary counter, and some ram, and that ends up >>>> emulating a spinning disk. The device only supports 2 functions, select >>>> a block address, and read/write a byte. Each time you select a block >>>> address, the binary counter is also reset to 0. Each time your read or >>>> write a byte, the binary counter is also advanced by 1. A block has >>>> 1024 >>>> bytes. So You select say block 40, then just read 1024 times to read >>>> the >>>> entire block. Like picking a track number and reading the track. >>>> >>>> https://github.com/bkw777/NODE_DATAPAC?tab=readme-ov-file#minindp >>>> >>>> But this needs to connect to the system bus and that's inconvenient on >>>> a >>>> Model 100 because it would need to be on a cable extending out to the >>>> back of the machine. You can actually use the Model 100 adapter portion >>>> of a DVI (Disk/Video Interface) cable for this. >>>> But really it's only good on a 102 or 200 where it just plugs directly >>>> onto the back of the machine. >>>> >>>> And what you get is disk space not ram. You could get disk space in a >>>> generally more convenient and flexible form from Backpack or PDDuino >>>> because those use the TPDD protocol, for which there are several bits >>>> of >>>> compatible software and hardware. IE, you have a choice of a few >>>> different kinds of TPDD driver software to run on the 100, and then the >>>> drive can also be used by other machines. the TANDY WP-2 has built-in >>>> tpdd support in it's firmware. You can connect a real TPDD drive or a >>>> backpack/pdduino to a PC and there are several softwares to access the >>>> drive or emulate a drive in any os, since the connection is just rs-232 >>>> and the protocol is known. >>>> >>>> While the RAMPAC-alikes there is no pc software to access the drive, >>>> and >>>> no hardware adapter to somehow connect it to a pc anyway. There are a >>>> few utils that made it a little more convenient to move files between >>>> the rampac and a tpdd, so to move files between rampac and pc you would >>>> use a 102/200 in the middle with the pc running a tpdd emulator. >>>> >>>> Still it has some little advantages. Small and simple. The driver >>>> software is smaller than most TPDD dos's, much smaller than TS-DOS but >>>> larger than Teeny. And it holds 512k. >>>> >>>> And the low level hardware interface is so simple and easy to operate >>>> directly even from basic, that you can actually use the raw space >>>> almost >>>> like ram if you are writing your own program. >>>> >>>> I have a 1 Meg version that actually has the entire hardware interface >>>> described right on the silkscreen on the back. because it's basically >>>> just 3 instructions with a tiny bit of explanation for the possible >>>> values for each. The normal RAMDSK software doesn't know how to access >>>> the extra space beyond banks 0 & 1, so the only way to use that is to >>>> write your own program that accesses banks 2 & 3 directly and uses it >>>> as >>>> raw space. >>>> >>>> TPDD is not convenient to access at the low level. It's only convenient >>>> at the user level using TS-DOS. Although TS-DOS does provide some hooks >>>> to provide high level file access functions in basic or from machine >>>> language. >>>> >>>> -- >>>> bkw >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> > >>>> > Chris >>>> > >>>> > On Tue, Nov 19, 2024 at 7:44 PM Bert Put <[email protected] >>>> > <mailto:[email protected]>> wrote: >>>> > >>>> > Hi Chris, >>>> > >>>> > Not the screen so much, but your REX will already give you oodles >>>> of >>>> > RAM >>>> > in banks of 32K. So you can swap out and in, as many RAM banks >>>> as your >>>> > REX has space for. >>>> > >>>> > I just discovered that recently while playing with my (original) >>>> REX, >>>> > M-100 and T-102. >>>> > >>>> > Cheers, Bert >>>> > >>>> > >>>> > On 11/19/24 17:59, Chris Kmiec wrote: >>>> > > I have to admit, I have not been following the latest >>>> > developments for >>>> > > the 100/102. I have the backpack, REX# and REXCPM, but they >>>> have >>>> > been >>>> > > sitting lonely as for the past year or so my hobby time has >>>> been >>>> > taken >>>> > > over by the HP 71b. >>>> > > >>>> > > Anyway, I want to start playing with the 100-series again, but >>>> > have a >>>> > > question - are there any modern upgrades for the LCD screen and >>>> > increase >>>> > > in RAM beyond the 32Kb? >>>> > >>>> >>>> -- >>>> bkw >>>> >>>>
