November 23, 2022

the MOD_EMUP protocol

From a study of the ISA board schematic and cable, I have learned the following. We have two 8 bit ports as follows: 
2E0 -  the "ID port"
2E2 -  the "data port"
The ID port is a write only port, the data port may be read or written. You select a register in the EMUP by writing first to the ID port. Then you can read or write from that register using the data port.

Of course these addresses assume you have the jumpers set for a base address of 0x2E0, and they should be changed accordingly if you use a different jumper setting.

There is open source software available for the ALL03 programmer, which is a close relative of the EMUP. It remains to be verified if all the register addresses work the same way.

The following document is part of the ALL03 software (in ALL03/src/doc) and is valuable and instructive:

Known registers

The following is from the all03info file. For more details, see that file. 
0xe5 - DAC "VOPID" 10.2 to 25.5 volts with 0.1 volt resolution
0xe6 - DAC "VHHID" 5.1 to 15.3 volts with 0.06 volt resolution
0xe7 - DAC "VCCID" 0.0 to 10.2 volts with 0.04 volt resolution

0xe0 - TTl0  40 pins on test socket, TTL control
0xe1 - TTl1
0xe2 - TTl2
0xe3 - TTl3
0xe4 - TTl4

0xe8 - VOP0  40 pins on test socket, VOP control
0xe9 - VOP1
0xea - VOP2
0xeb - VOP3
0xec - VOP4

0xf0 - VHH0  40 pins on test socket, VHH control
0xf1 - VHH1
0xf2 - VHH2
0xf3 - VHH3
0xf4 - VHH4

0xed - VCC0  16 bits of VCC control
0xee - VCC1

0xf5 - VHHEX0 16 bits of "extra" VHH control
0xf6 - VHHEX1

0xef - OTHER  8 bits of "other" control

0xf7 - LED (bit 3 controls the "GOOD" led

Examples

The ALL03 source code has examples for the Atmel (now microchip) AT89C52 controller. This is an obsolete (naturally) controller based on the 8051 core with 8K of flash in a 40 pin package. The AT90S8515 is another example. It is another obsolete part with 8K of flash in a 40 pin package, this time with an AVR core.

Perhaps more accessible is 27c512a for the well know 27c512 eprom chip. This at least I have chips to experiment with as well as printed datasheets.

Pin control circuitry

The following diagram was distributed with the ALL03 sources. It shows the circuitry that drives a single pin. I need to poke around on my EMUP unit and see if the pin circuitry is the same and/or augment this diagram accordingly.

Have any comments? Questions? Drop me a line!

Tom's Electronics pages / tom@mmto.org