Issue 2 PCB’s contain probably the widest variety of ULA types – very early ones had 5C102E ULA’s (with cockroach), then 5C112E, and very late ones had 6C001E-5 and 6C001E-6 ULA’s.Įxternally the most obvious change is to the keymat which is now blue in colour, although very early Issue 2’s may come with the Issue 1 keymat as mentioned above.Īpproximately 500,000 Issue 2’s were produced. This issue is otherwise operationally identical to the Issue 1 circuit. IC designations are on the PCB silkscreen and the lower RAM is installed in order, bit 7 to bit 0 left to right.
Upper RAM is limited to Texas Instruments TI4532, but OKI 3732 can be used with a minor modifcation.
#Sinclair zx spectrum full
It also has provision for the full 48K of RAM on the main PCB. This followed the Issue 1 quite quickly in August of 1982, and was the first Spectrum issue to be laid out using CAD tools. Proceed with caution if buying a machine of unknown provenance without pictures of the PCB itself.Īpproximately 16,000 of these machines were produced. The grey mat and/or hole are sometimes present on very early Issue 2’s however, and some very late Issue 1 machines may have a blue keymat.
If the 32K expansion daughterboard is fitted, its decoupling capacitors will be visible through the expansion port. Visually, they can be most easily identified by their grey, ‘dead-flesh’ feel keymat and a small adjustment hole on the underside of the machine. Y, U, V and VID ‘straps’ are present on the PCB, if wire links are installed here then the relevant signals are carried out to the edge connector. The regulator and heatsink are situated at the bottom right of the PCB, the heatsink is a little undersized and such the machine can suffer from overheating problems.
#Sinclair zx spectrum mods
Can suffer from blue/yellow screen tinting which can usually be resolved by adjusting VR1/VR2, however other mods are sometimes required to completely cure this. There are no IC designations on the silkscreen, and the lower RAM is not properly arranged in bit order as found on later issues. It can only take 16K of RAM on the main PCB and required a daughterboard to supply the upper 32K, which plugs into two sockets at the top of the PCB. This has hand drawn PCB traces and has a prototype ‘feel’, and was laid out by Stuart Honeyball, whose later employment included Miracle Systems. The first Spectrum ever produced, manufacture commencing in April 1982. You can view a gallery of all the PCB revisions mentioned in this article at the bottom of the page. Cost reduced versions of the 128 architecture with some incompatibilities. The grey +2 was Amstrad’s first machine and was heavily derived from the 128 architecture.
First produced for Investronica of Spain, later released in UK. Here’s a brief overview of the various Spectrum PCB revisions, this section is split into three main areas:
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