Flakey HP 70: post modified as RAM Chip identified.

[Didier Lachieze]

According to this table the following chips are used on the HP-70:

Code:

part number   models                description    vendor(s)              notes
---------------------------------------------------------------------------------------------- 
1818-0078     35, 45, 55, 70, 80    CTC            AMI, Mostek MK6021P 
1818-0116     70                    ROM, 1024*10   AMI 
1818-0117     70                    ROM, 1024*10   AMI
1820-0993     45, 46, 70 , 81       RAM, 10*56     Mostek MK6036P         replaced by 1820-1393 
1820-1128     35, 45, 55, 70, 80    clock driver and reset, 16 pin DIP     
1820-1169     35, 45, 55, 70, 80    ARC            AMI, Mostek MK6020P

The RAM being the same on the HP-70 as the one on the HP-45 this can be an easy replacement source.