[FRAM71] Pre-Production Batch

[Hans Brueggemann]

i have currently three FRAM71 with the 1MByte modification on my bench and, while the soldering job isn't too demanding (i don't have a steady hand, hence i'm just using a big spade shaped soldering tip and a lot uf flux and then swipe it across the pins, https://www.youtube.com/watch?v=5uiroWBkdFY), the unconnected pins are indeed very difficult to discover. however, with bankswitching enabled, POKE "2C000","FF" followed by a PEEK$("2C000",2) points you directly to the affected data lines, for example.

if you have a scope, you may want to try an endless loop such as
10 POKE "2C000", "FF" @ GOTO 10
and check signal activity on all lines directly at the bottom FRAM (i.e., at the pad on the pcb) and then check whether the top FRAM pins show the same amount of activity.

while testing with POKE/PEEK$, you may observe various symptoms and causes:
1) data read differ from data written
missing data line, or missing address line
2) data read back is always zero
missing !WE, !OE, !ZZ, VDD (!WE, !OE are very short pulses)
3) data read back is correct, but HP-71B doesn't assign memory correctly
missing address line

hans
(btw... still waiting for some users to respond and send me their ship-to addresses)