BETA VERSION NOT A FINAL, IN TESTING PROGRESS , CONTRIBUTORS WANTED.
** This Arduino project tests 256 x 4 bit dram chips: hyb-514256b if they are faulty.
These chips and similar ones, are the base memory chips of an Amiga 500 and 500+ computer.
Unfortunately something is missing and the test can’t work for 100% but is giving some results.
So it is in deployment progress and in beta testing.
Contributors may welcomed to help fix this to offer it to public.
The 514256b ram chips are 4bit 256KB with 20pin and in A500+ there are 8 of them.
So for the A500+ we have: 8x4x256K = 8192 Kbit = 8192 / 8 = 1024 Kbytes = 1Mb.
This project is on your own risk, and not intended for professional use. You can use it on your own risk and I am not responsible for any damage by any reason. Before you make the Arduino software test, you must check first with a multimemeter if your chip is broken to protect your hardware, see bellow.
A multimeter for checking if chip is broken. You will also need a breadboard connecting cables and of course the ram chips to check. Also a ziff socket will be good idea for securing the chip but the breadboard holes can also be used.
1- Check for shorted Vcc 2- Inputs Ax, /CAS, /RAS, /WE, DIN must be high-Z. If shorted to 0v/5v, it's broken. 3- Output DOUT must be high-Z in the absence of RAS/CAS activity. 4- Output DOUT is push-pull AFTER the RAS/CAS read sequence (see datasheet). If it's high-Z, it's broken.
Chip - Arduino Arduino - Chip
Description / AA Description / Arduino Number
CHIP ARDUINO ARDUINO CHIP
-------+----------- ----------+--------
IO1 1 A1 15 PD2 2 17 CAS
IO2 2 A2 16 PD3 3 4 RAS
WE 3 A5 19 PD4 4 -- --
RAS 4 3 PD3 PD5 5 6 A0
NC 5 -- -- PD6 6 7 A1
A0 6 5 PD5 PD7 7 8 A2
A1 7 6 PD6 PB0 8 9 A3
A2 8 7 PD7 PB1 9 11 A4
A3 9 8 PB0 PB2 10 12 A5
VCC 10 +5V +5V PB3 11 13 A6
A4 11 9 PB1 PB4 12 14 A7
A5 12 10 PB2 PB5 13 15 A8
A6 13 11 PB3 -- -- 5 NC
A7 14 12 PB4 +5V +5V 10 VCC
A8 15 13 PB5 14 A0 16 OE
OE 16 A0 14 15 A1 1 IO1
CAS 17 2 PD2 16 A2 2 IO2
IO3 18 A3 17 17 A3 18 IO3
IO4 19 A4 18 18 A4 19 IO4
VSS 20 GND GND 19 A5 3 WE
-- -- 4 PD4 GND GND 20 VSS
I would like to thank first of all the Amiga and Commodore community for keeping alive these very old but so beloved and wonderful machines, and all the people who spend a lot of time to share their work with others:
iss: for DRAMARDUINO - Dram tester with Arduino
http://forum.defence-force.org/viewtopic.php?p=15035&sid=17bf402b9c2fd97c8779668b8dde2044
Commodore 64 hardware test tools
jamarju
https://github.com/jamarju/c64_test_tools
Chris Osborn:
http://insentricity.com/a.cl/252