Vintage Computer Festival wrote: OK, the details. The machine is the compucolor II. There are two 2708-equivalent ROMs to hold character generator data (they are mask programmed ROMs, not actual 2708s). Because compucolors are so scarce, I didn't want to risk damaging anything by taking the ROMs out and putting them back in, even if it is a relatively simple job. I wrote a program on the compucolor to fill the display RAM with all the characters. One ROM is just the bitmapped graphics mode, yielding the 256 possible combitions of fat pixels in a 2x4 pixel grid. There was no need to dump that. Recreating the program on the compucolor, it was something like this: 10 B=4096*6:REM BASE ADDRESS OF DISPLAY RAM 20 FOR I=1 TO 16 30 FOR C=0 TO 127 40 POKE B,C:REM ASCII CHARACTER VALUE 50 POKE B+1,7:REM WHITE CHAR ON BLACK BACKGROUND 60 B=B+2 70 NEXT C,I 80 GOTO 80 The compucolor display is a 64x32 character cell grid with two bytes per character. The even byte is the ascii value; the odd byte is the attribute byte including fg/bg colors, blink, and plot mode. The MSB of the ascii value tells the logic to line double the character rows, showing the top half if in an even row and the bottom half in an odd row such that double heights characters can be intermixed with single height charactes. None of that matters to the character ROM, so the above code just draws the 128 unique character values. There are eight rows per character cell, so a 1KB ROM is enough to hold the information. The 1631 is set up to monitor the 10 address lines, the 8 data lines, and a clock signal elsewhere in the logic that fires when the ROM output is being sampled. Fortunately, you can set up all the logic analyzer stuff manually before entering HP-IB controlled mode. My original fear was that I was going to have to set everything up via the HP-IB interface. Make sure the 1631 is in HP-IB slave mode. In my case I made it address 02, so that from the HP-87 it appears as device 702 (which will be evident in the code below). I had to hook up a serial port adapter to the hp87 to get the data to my PC. The initial part of the program below sets up the right bits & rates to allow that to happen. The serial port is device address 10. It would have been possible to program the logic analyzer to look for a specific address and then capture it, but it was easier for me to be statistical. When I tell the logic analyzer to RUN, it could start sampling at just about any phase in the process. The depth of the trace memory is only 1024 samples, and not all clocks have valid data, so a single run will never catch all 1024 ROM adddresses. Instead my program keeps track of which addresses have been capture already and just keeps sampling until all values have been seen. Now the hp-87 code. To prove that I'm not an aesthete, note the liberal use of GOTO below. :-) 10 DIM ROM(1024) 20 DIM DONE(1024) 30 FOR I=0 TO 1023 @ DONE(I)=0 @ NEXT I 40 LEFT=1024 50 ! 60 ! 70 ! set up the serial port 80 STATUS 10,0 ; S@ IF S=2 THEN 100 90 DISP "Device 10 isn't a serial port" @ STOP 100 CONTROL 10,1 ; 0 ! no interrupts 110 CONTROL 10,3 ; 15 ! 9600 bps 120 CONTROL 10,4 ; 3 ! no parity, 8b 130 CONTROL 10,5 ; 48@ REM hw flow control 140 ! 150 ! 160 CAPTURE: 170 OUTPUT 702 ;"LM" ! LIST menu 180 OUTPUT 702 ;"RN" ! RUN 190 WAIT 1000 ! sleep one second 200 OUTPUT 702 ;"SB2" ! status byte 210 ENTER 702 USING "#,B" ; ST 220 IF BIT (ST,1)=1 THEN 240 230 DISP "Waiting on capture" @ GOTO 190 240 OUTPUT 702 ;"TS" ! dump trace state 250 ENTER 702 USING "#,2A,W,7X,1X,B" ; C$,BYTES,FMT 260 IF C$="RS" THEN 280 270 DISP "Response RS expected" @ STOP 280 IF FMT=0 THEN 300 290 DISP "Format 0 expected" @ STOP 300 ENTER 702 USING "#,X,W,2X" ; SAMPLES 310 DISP "SAMPLES:";SAMPLES 320 FOR I=1 TO SAMPLES 330 ENTER 702 USING "#,B,B,B,B,2X" ; B0,B1,B2,B3 335 GOSUB 500 340 NEXT I 350 ENTER 702 USING "#,X,2X" ! skip revision code and CRC 370 IF LEFT>0 THEN CAPTURE 380 ! 390 ! 400 ! dump results to the serial port 410 FOR I=0 TO 1023 420 H$=DTH$ (ROM(I)) 425 FOR J=1 TO 8 @ IF BIT (ROM(I),8-J) THEN I$[J]="#" ELSE I$[J]="." 426 NEXT J 430 OUTPUT 10 USING "4X,2A,4X,4D,4X,6A" ; H$[3,4],I,I$ 440 NEXT I 450 GOTO 1000 460 ! 470 ! 500 ! pick apart the data 520 POD4=BINAND (B0,7)*64+B1 DIV 4 530 POD3=BINAND (B1,3)*128+B2 DIV 2 540 POD2=BINAND (B2,1)*256+B3 550 DAT=BINAND (POD4,255) 560 ADDR=BINAND (POD2,3)*256+POD3 DIV 16*8+BINAND (POD3,7) 570 IF DONE(ADDR) THEN 600 580 DONE(ADDR)=1 @ ROM(ADDR)=DAT @ LEFT=LEFT-1 590 DISP "ADDR ";ADDR;"=";DAT;", LEFT=";LEFT 600 RETURN 1000 END