The "Big Issue" about the ZX 48K rubber key Spectrum . Which Issue is best?

There is no easy answer as every 48k rubber keyed Speccy owner will have their own favourite so it will be pretty subjective . But my favourite at the moment is an Issue 6A rubber key 48k . I got it cheaply on Ebay , it works well and maybe by by that time they had sorted out the problems and by then there was only 1 socketed chip remained , I think , so there fewer oxidization problems on the legs of the chips. So did Speccies get better and more reliable as time went on ? I think that maybe they did but nothing is certain ............


  • Yes, they got better as each issue board was produced, as Sinclair became aware of problems, if it was a straightforward fix, they fixed the problem in the next board issue.

    Also the later ULAs were more reliable. The on board switch mode power supply was more reliable in later issues (and on earlier boards if they were properly serviced).

    The only problem with the later issue boards (issue 5 and 6A), is the extra custom chip IC27 (ZX8401 / PCF1306P, see here). The only replacements are modules
    as replacement chips are not available.

  • Many issue 4 boards (A/B/S) had a faulty CPU, if I remember correctly, which caused problems with the Interface 1, Multiface, and divIDE. (Not an inherent issue with the board itself, though, so replacing the CPU with a known good one fixes the problem.) The ULA, however, is much improved and produces a noticeably better picture.

    Generally speaking, anything starting from issue 3 (or 3B) is a good choice.

    To answer your question: yes, the Speccy did get better with each board revision, but not necessarily more reliable (see Mark’s explanation above).
    Every man should plant a tree, build a house, and write a ZX Spectrum game.

    Author of A Yankee in Iraq, a 50 fps shoot-’em-up—the first game to utilize the floating bus on the +2A/+3,
    and zasm Z80 Assembler syntax highlighter.
    Member of the team that discovered, analyzed, and detailed the floating bus behavior on the ZX Spectrum +2A/+3.

    A few Spectrum game fixes.

  • Reply to both.

    Thanks for the ideas and information on this .

    The Spectrum was a success ,it sold in large numbers to some product "rationalization" would be normal as money is saved by "getting better at it" so there is an incentive to sell better product . But what about the small "backward steps" than also sometimes accompany this otherwise general improvement?

    I Think Mark may have mentioned one of the snags of the "late in the life cycle rationalisation"process .One effect of this "lateness" effect is the shortage of spare parts nowadays for some of the later Speccy Issues , so today , for instance , these parts can be hard to find or even totally non existent : it does seem to be the case therefore , that a lot of the early high volume sales were with relatively "unrationalised" Speccies and the better more reliable and functional models appeared fairly late in the day in smaller numbers. (and Guesser has mentioned a "scarce part" no longer available for the later +2 variant models) But maybe , some of the earlier Speccies could be said to "shine" in other areas than mere functionality: value or collectability maybe?

    So on the question of "which is best"?" then the response "Best for what?" comes in . There are different Speccy retro genres and categories , other than mere functionality . But these genres are quite specialist so asking for an answer for each of these is a bit of a "tall order" . But nevertheless someone might come up with something interesting on this.
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