The programming specs suggest CE pulses of 100 microseconds +/- 5 microseconds at up to 10 repeats, and Vcc=6.5 volts and Vpp=13.0 volts, both +/-0.25 volts. Maybe he'll have to shell out the $300 or $400, since he wants to continue with this. But I know I'm not going to have time to build it, and I'm sure Rick wants a plug and play that he can hook up to his PC. I like the idea of a Prop based programmer. At the time I could spin BC, DE and HL pretty fluently, a hazy hazy memory now. The T102 was also at the heart of my original OWL data loggers.

And I also manufactured RAM expansions called the 'extram' and the 'XR4' and the RAMpak, and provided operating system extensions to used the additional banked memory. It used a special circuit board material called 'bendflex' that has since been discontinued. We use a bridge from the programmer to an SOIC clamp to program the chip, and the large plated through holes on the edge of the circuit board are cut through to expose 28 half-moon contacts that press down into the option socket.īack in its heyday, I made a different design of option ROM adapter called ROMBO that I sold a lot of through the magazines. Not only is it a proprietary deep socket, but in their great wisdom Rat Shack switched the pin connections so that it doesn't correspond to the standard 27C256. I provide Rick with the OTP soic eproms mounted on a carrier that fits into the option ROM socket. Yes, amazing, there are still a lot of them out there running printing presses and laundromats and the in the cruisers of small police departments in the desks of a certain breed of news reporters and in classrooms. He has an ongoing evening business in buying and selling Tandy 100, 102 and 200s, and in providing add-on ROMs.

We have an Andromeda Labs PROM burner, which supports lots of devices.Īdded detail: I've been using the 28-pin DIP package.This programmer is for my friend, Rick Hanson, who operates Club 100.

(All of the EPROMs have seemed pretty good for this.) Would the 28C family be a good place to look? Robustness to student wiring mistakes would be great. I'd be happy with as few as 8 address bits (we use two LS163s for the PC), although I doubt anyone makes something that small. It doesn't need to be pin-compatible, although that would be nice. I started with the 27C256 EPROM but switched to the 29C256 EEPROM, which has now gotten hard to find.Ĭan anyone recommend an EEPROM (I'm sick of UV erasers) that would be a good replacement? Specifically, it should be reasonably priced, reliable, easily available and likely to remain so. The instructions are read by a low-speed TTL computer they build. I teach a hands-on computer architecture course in which the students burn their programs onto an EPROM with a commerical PROM burner.

27c256 eprom programmer