Sinclair Research ZX Spectrum - Issue 2 Board; Issue 3 Board

4.2 Issue 2 Board
The ICs used on this board are as follows:
1C TYPE
IC15 - IC22 TI 4532-3 or TI 4532-4 200ns (or 250ns)
IC23 74LS32
IC24 74LSOO
IC25, IC26 74LS157 (NOT National Semiconductors)
NOTES: (1) All external RAM ICs must be of the same type
(i.e. all -3 or -4 variants).
(2) LINK 3 on the board (IC26, pin 10) should be fitted
if IC15-IC22 are type 4532-3.
(3) LINK 4 should be fitted if IC15-IC22 are type 4532-4.
.3 Issue 3 Board
The ICs used on this board are as follows:
1C TYPE
IC15 - IC22 TI 4532-3, TI 4532-4 or OKI
MSM3732 200 ns (or 250ns)
IC23 74LS32
IC24 74LSOO
IC25, IC26 74LS157 (NOT National Semiconductors)
NOTES: (1) All extension RAM ICs must be of the same type.
(2) Two links must be fitted on the board (grid
located between edge connector and m/c jack
socket) depending on memory manufacturer and
type (high or low enable). See Figure 4.4 for
link positions vs manufacturer and 1C type.
4.20