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 > >
