Sinclair ZX Spectrum

Sinclair ZX Spectrum Service Manual
Spectrum For Everyone https://spectrumforeveryone.com/
38
Notes:
• All external RAM ICs must be of the same type (i.e. all -3 or -4 variants)
• LINK 3 on the board (IC26, pin 10) should be fitted if IC15-IC22 are type 4532-3
• LINK 4 should be fitted if IC15-IC22 are type 4532-4
7.3.3 Issue 3 Board
The ICs used on this board are as follows:
IC
Type
IC15-IC22
TI 4532-3 or TI 4532-4 or OKI MSM3732 200ns (or 250ns)
IC23
74LS32
IC24
74LS00
IC25, IC26
74LS157 (NOT National Semiconductors)
Notes:
• All extension RAM ICs must be of the same type.
• Two links must be fitted on the board (grid located between edge connector and mic jack socket)
depending on memory manufacturer and type (high or low enable).