Viser opslag med etiketten EPROM. Vis alle opslag
Viser opslag med etiketten EPROM. Vis alle opslag

fredag den 5. september 2014

Historic PROM burner: The DATAIO model IX

So, i bought this some time ago, a really interesting artifact of computer/digital electronics history.

It is, as far as my research go, nothing less than the worlds first microprocessor controlled PROM burner!

Yup, that's it. Pretty good condition, except for one missing button cover on the EDIT. It can check memory, copy it, browse through addresses, and many other functions. It has a parallel Dsub25 connector on the back, for "remote operation" - whether that means having "slave" programmers for multiple chips, or the unit being able to be controlled by other systems. I haven't found ANY documentation on this; no manual, nothing. the only reference to it is a note on DATA IO's website, under a company history timeline.

On the same timeline, they state that model 19 is the first microprocessor controlled burner (with MC6800) - That is wrong, since this model is earlier, and IS controlled by a 6800, making THIS the first. Though, whether it's the worlds first or the company's, I really haven't the foggiest.

THE GUTS

The case is in fiberglass, and split color blue/white, and is mounted on a 8 mm aluminum bottom plate - really adds some weight.

The computer part, which is what we want, is mounted in a little rack system, with a backplane bus of chained card-edge connectors on ribbon cable. There are 4 boards, with those lovely "ears" for releasing them from the rack.

************************THE PROCESSOR BOARD************************


If that ain't retro, I don't know what is! The memory is shared over 4 chips - 2x 2708 1K EPROMs, the white ceramic with gold windowframe/legs! i had to cover them, i were afraid the flash of the camera could damage the memory, so the windows are covered with masking tape. The plastic DIP24 with the sticker must be system ROM, and the MC6810 is the typical RAM to go with the MC6800. This RAM, is probably system RAM, there must be a reason why the RAM is split on two boards - more on that later. The shiny can is the MC6871A - an oscillator / two phase clock for the 6800. Not much else, a little logic and some jumpers. Notice how the address range of the memory is labeled in the silk screen: C600-C7FF and so on. That's neat!

************************MEMORY BOARD************************ 


 This is the RAM board. Little more than 2 AM9131ADC 1024x4 SRAM chips - yes, Advanced Micro Devices, AMD. Apparently, This can be expanded, by the two empty sockets. The RAM IC's is in the purple/grey/gold packages - same as the 6800 itself. I believe this RAM is for holding the PROM code in memory.

************************ I/O ************************

The I/O is again, as far as i can tell, very much standard 6800 peripheral stuff:


The 24 pin DIP package is the MC6850 ACIA Asynchronous Communications Interface Adapter, acting as an UART. The 40 pin package is the MC6821 peripherals adapter, driving, by the looks of the bus, the header connector top left, which goes to the front panel. The smaller second card edge connector (right) goes to the DSUB 25 connector. And a baud rate switch for the ACIA - what would happen if you activated more than one?

The main programming cards and IC sockets are connected directly to the main system bus, and consists of a set of two chip specific cards: A digital, dealing with timing and such, and an analog, setting voltages. I have yet to find any references as to what PROM my system is set up for, but changing chip for this model of burner must be quite a challenge. The analog board also needed calibration.

There's much more, so I'll probably do a follow up, but this is a brief description (ha. BRIEF) of the microprocessor/computer based parts.     

Burning EPROMS the stupid way

So I'm reaching a point where I'll need to work on my ROM. Step one involves little more than some tests and the ability to punch in programs via the input ports. The system ROM is a 2716 EPROM, because i think it's neat because it's pin compatible with my RAM, so i can reuse the board later on. I found my EPROM burner, and wept. I completely forgot, it works, but it is.. not my fines piece of DIY gear. ADDR and DATA is set with a sharp pencil and DIP-switches, and binary data readout on the little floating board.

The only thing even remotely nice about it is the genuine 3M TEXTOOL socket, (not installed on the pic).


Since I'm only at 60-100 bytes at the moment, this abomination is adequate, but i really need to make a more optimized one. With HEX rotary switches, 7seg readouts, and "jump to next address" button.