TRS-80 Model 1 replica coming?

[jrd]

I know in the past, some members have wished for a full TRS-80 replica kit, instead of just kits for an expansion interface or other peripherals.

Well, pski's "Model 1 Wikipedia" was featured on Hackaday a few days ago, and got a little bit of attention.

http://hackaday.com/2015/04/28/hackaday-retro-edition-trs-wiki/

In the comments, there was talk of no replica existing, and that started off a discussion and questions. It looks like some people are interested in making one. Let's see if it leads to anything!

 

[BartH]

First steps

First steps

The first steps towards a TRS-80 Model 1 replica have been taken. The first thoughts on components are:

- Z80 CPU, probably NMOS
- ROM - probably FLASH
- RAM - SRAM with RAS CAS on expansion connector.
- CPLD - Glue logic / video. Xilinx XC9572XL (easy to solder) or Altera EPM750 (cheaper to program).
- OP-Amp - for cassette port filtering.
- 7805 V Reg

So a 'real' Z80, all logic in the CPLD, a standard connector for peripherals (IDE pins, no card edge) and a 20 pin-connector for the keyboard (so it can be used inside a normal, but defective, TRS-80 with an intact keyboard). Compatible on the outside so to speak!

It is not my project but I'm helping out with information and documentation. The complete project can be found at:

https://hackaday.io/project/5565-trs-80-compatible-clone

 

[Al Hartman]

A Model I replica would be nice if it would fit in the original case like the TC III board, but it doesn't have to.

For me, a perfect Model I/III (I would pick one, perhaps emulating the 4 would be best) replica would:

Have 48k/64k/128k compatible with CP/M
64/80 Column Mode compatible with CP/M
Composite or VGA output (Peter has already figured this out with the MISE project)
PS/2 or USB Keyboard
Mounting in a Model I/III case optional. I'd prefer mounting in an ATX case with a pair of half height 360k drives.
Cassette Port for sound out
Orch 80 compatible sound out or the stereo Orch 8- whose name I forget.
Alpha Stick Joystick Port
Real Time Clock
Floppy Controller (You CAN still get the chips, and there are reimplemented cores for FPGAS)
Serial Port (Use PC Standard Connector)
Parallel Port (Use PC Standard Connector)
TRS-80 Expansion Port
Turbo speed that throttles down for FDD I/O or via Keyboard press

I wouldn't worry about the ROMs, none of the emulators do. You can sell the board without ROMs, and the user can load them onto an SDCard to boot it.

A 1.0 could just be the Model I keyboard alone with RAM, Video, Keyboard, Cassette, No FDD, Serial, just to debug the core. Then, a 2.0 could add the Serial, parallel, FDD and other options as a plug-in Expansion Interface, or as a larger 2.0 board.

 

[Al Hartman]

http://www.trs-80.org/norcom-tc-iii/

 

[pski]

@Al, I would add Model III hi-res graphics compatibility as well.