* * * Sinclair QL - Build Standards, PCB Issues, Chipset & ROM versions * * *

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Added: February 28th 2002 | Last updated: February 4th 2022

Wow: With at least 20 Build Standards using at least 16 PCB Issues only approximately 140'000 QLs were manufactured!

Sinclair QL Design and Production Review by a CTO

About Build Standards, Serial Numbers, Motherboard, Chipset & ROM versions

Machine Build Standards & Serial Numbers

Sinclair QL professional computer Build Standards & Serial Numbers do follow the following notation and format: Dxx-yyyyyy or S*xx-yyyyyy where:

  • D stands for manufacturer named Datatech, short for (Thorn EMI) Datatech. Earliest machine ever seen (in December 2019) is D02-001058. Original D02 build standard QLs had ZX8302 chips manufactured 8414. Latest machine even seen (in June 2019) is ##8-123538 where ##8 is a misprint of D18 (ZX8302 chip manufactured 8534).

  • S stands for manufacturer named SAMSUNG. Earliest machine ever seen (in September 2013) is SG18-001002. Latest machine ever seen (in July 1990) is SG18-010800. * in S*xx-yyyyyy is optional, stands for the designated target market, only use case was G for German Edition.

  • xx is the build standard number, where D machines known to exist are in the range 02 (most likely also on earth at one time was 01) to 17 plus ##8 which is a misprint of D18 (the only machine ever seen is ##8-123538); S machines known to exist are having their own build standard 13 (S13 for North American markets) - this is based on the D14 build standard - and 18 (SG18 for German speaking markets) - this is based on the D17 build standard. To sum up, 20 different build standards were created.

  • yyyyyy is the sequential serial number, per manufacturer (Datatech), respectively per manufacturer Edition (SAMSUNG), each starting from 001000 (or 001001).

  • The S13 Build Standard machines have the following FCC ID: EHF 9QN QL-US-85010, issued 1985-04-25.

    PCB (Motherboard) names, dates and issues

    Sinclair QL PCB (Motherboard) names, dates and issues have the specifics as following:

    Sinclair_QL_prototype_board_only_PCBA_ZX-83_1983_ISS2_component_side-CIMG2658-cropped.jpg Sinclair_QL_prototype_board_only_PCBA_ZX-83_1983_ISS2_solder_side-issue2mb4_cropped2.jpg
    Sinclair_QL_1984_ISS_4_PCBA_component_side-P1060612-cropped.JPG Sinclair_QL_1984_ISS_4_PCBA_solder_side-PM_QL_2a-by_PH-cropped.jpg

  • (Thorn EMI) Datatech made Dxx-yyyyyy QLs have seen 7 PCB issues. Known to exist are ZX-83 1983 ISS.2 with date code 8350 (see pictures above), still dated 1983, still named by the QLs codename ZX-83, ISS.4 from now on dated 1984 and named QL (see pictures above), ISS.5 (earliest date code 8415), ISS.6 (earliest date code 8447) and ISS.7 (5). Most likely also on earth at one time were ISS.1, ISS.3 (2, missing in action).

  • SAMSUNG made S*xx-yyyyyy QLs have seen 9 (!) PCB issues. Instead of ISS which is short for issue, they are issued as US which is short for United States Edition. Known to exist are US3, US5, US5.1, US5.2, US5.3, US6 (6). Most likely also on earth at one time were US1, US2, US4 (3, missing in action). SAMSUNG made QL had the inside of the plastic case silver-coated and had other measures to make the QL comply with stronger US FCC and German VDE standards. Such measures include capacitors added piggyback on some chips or at some lines, diodes added piggyback on the RGB video signal pins of the ZX8301.

  • Sinclair introduced IC38 (a HAL) on ISS.6 in autumn 1984 with build standard D14. ISS.6 was the starting point for the SAMSUNG made PCBs with the naming US*. US stands for United States (the initial target market for SAMSUNG made QLs), not to be confused with ISS which stands for issue. US5 is not an issue 5 (ISS.5) board, it's more a derivate from ISS.6.


    Sinclair QL Chipset components and issues are named as follows:

  • ZX8301 Master Chip (MC). Made by Plessey in the UK. 2 issues are known to exist CLA2310 (1st gen, used in Dxx QLs) and CLA2345 (2nd gen, used in all S*xx QLs and late Dxx QLs).

  • ZX8302 Peripheral Chip (PC). Made by NCR in the USA. 1 issue is known to exist 0371725.

  • 8049 Intelligent Peripheral Controller (IPC). Licenced Intel 8049 with 2KB custom firmware by Sinclair Research Ltd., chips made by either NEC or PHILIPS. 2 versions of the embedded custom firmware are known to exist 0.7 (used in chips made by NEC and PHILIPS) and 1.2 (used in later chips made by NEC only).

  • Firmware

    Sinclair QL ROM names and versions as follows:

  • FB (missing in action), FB.2 (first 32KB missing in action), PM, AH, JM, TB, JS, JSU, MGx, EFP, TY05, TY06. Those written in italic were only produced in EPROM form. The earliest seen masked ROMs are VTi made gold-plated CERDIP with date code 427 (1984 week 27) which contain the AH firmware.

  • Trivia

  • Gold-plated CERDIP Sinclair ICs were only used for sampling, for very first runs of the chip production. They were replaced by pure CERDIP and later by plastic package.
  • Gold-plated CERDIP Motorola MC68008 ICs were only used for the first 100'000 QLs. Then Sinclair purchased and used the cheaper plastic package.
  • Very early QLs often have a hand written number on (a small white round sticker on) the UHF modulator which numbers the machine before its serial number was heat stamped, e.g. the QL with S/N D02-001071 has written the number 72 on that small sticker on the UHF modulator, which indicates that the first serial number was 1000. Such early QLs have another small white round sticker with a blue / near the CTL2 socket on the PCB.

  • QLs failed to be completed on the production line and QLs not passed QA have no heat stamped serial number at all.

  • QL reworked/refurbished/repaired after DOA return have a white rectangular sticker with a printed number in the format AR1zzzzz, where A stands for AB Electronics, R stands for Rework and zzzzz is the sequential number of the rework.

  • In case only 32KB of the ROM code is in place, then the QL typical boot splash screen - the one where it prompts F1 and F2 - appears with no text (F1..., F2..., 1983...) in the windows.

  • Misinformation and misconceptions (fake news)

  • For decades many people and media stated that in the recall of early QLs by Sinclair Research Ltd. to equip ROM firmware, those early QLs were just scrapped at Sinclair and the customers got new/fresh replacements machines. This is simply not true, most of those QLs got reworked and sent back to the customers. Only if the rework failed, the machine not passing the QA tests, or the machine got damaged or lost, then the customer got a replacement machine.

    To get proof of the above, browse the Details and Story folders of the Picture Gallery (SQPG) and view the pictures. Please also see the next chapter About my QLs of this webpage.

    Although the original Engineering Specifications are lost, the original Service Manual holds most of the Engineering Specification.

  • About my QLs

    Lucerne, Aug 23th 2002 Over the years I collected QL computers and now own 9 QLs. From 6 of them you'll find pictures concerning "Build Standard-Serial Number", "CPU/Master Chip (MC)", "PCB view" and "PCB Issue/ROM version" on this page. Based on approved information and indications, I know that at least 121,821 English QLs (manufactured by Thorn-EMI-Datatech; 15 known Build Standards from D03 to D17; last known machine is D16-122821), 4'861 US QLs (manufactured by SAMSUNG in Korea; Build Standard S13; last known machine is S13-005861) and 9,800 German QLs (manufactured by SAMSUNG in Korea; Build Standard SG18; last known machine is SG18-010800 from 05/86) were produced.
    I'm still searching for an English pre-D04 (up to D04-001371 which I bought on ebay in July 2002) and an English post-D16 (from D16-122418 or better any D17) QL plus other European QL's (Sweden, Denmark, Spain, Greece, Italy, France). If someone knows how I could obtain such a machine, please let me know, Thank You very much!
    Luzern, 23.08.2002 Mittlerweile besitze ich 9 QLs, davon sind hier 6 bezüglich "Build Standard-Serien Nummer", "CPU/Master Chip (MC)", "Platinen-Ansicht" und "Platinen-Ausgabe/ROM-Version" abgebildet. Basierend auf von mir nachgeprüften Informationen und Indizien wurden mindestens 121'821 englische QLs (hergestellt von Thorn-EMI-Datatech; 15 bekannte Build Standards von D03 bis D17; letztes mir bekanntes Gerät ist D16-122821), mindestens 4'861 US QLs (hergestellt bei SAMSUNG in Korea; Build Standard S13; letztes mir bekanntes Gerät ist S13-005861) und mindestens 9'800 deutsche QLs (hergestellt bei SAMSUNG in Korea; Build Standard SG18; letztes mir bekanntes Gerät ist SG18-010800 vom 05/86) produziert.
    Ich suche noch einen englischen pre-D04 (bis D04-001371 den ich im Juli 2002 auf ebay gekauft habe) und einen englischen post-D16 (ab D16-122418 oder lieber einen D17) QL sowie weitere europäische QLs (Schweden, Dänemark, Spanien, Griechenland, Italien, Frankreich). Falls jemand weiss wie ich zu einem solchen Gerät kommen kann, bitte bei mir melden, Besten Dank!

    Factory rejected (Thorn EMI) Datatech made QL (no serial number but paper sticker on case shell, keyboard with wrong key caps, no MDVs) with ISS.5 PCB and AH ROMs (got it from Malcolm of QUANTA's London sub group in January 2002)
    no serial number...
    but a paper sticker
    SERial and ConTroL ports
    wrong key caps mounted

    Early pre-Issue 6 (Thorn EMI) Datatech made QL (S/N D05-002875) with ISS.5 PCB and JM ROMs (got it at QL2000 from QUANTA's London sub group)
    D05-002875 with D12 mods
    Plastic CPU, ceramic CLA2310
    no modifications
    JM ROMs piggyback

    Reworked post-Issue 6 (Thorn EMI) Datatech made QL with ISS.6 PCB and JS ROMs (no serial number but AR109323 AR1xxxxx sticker on new case shell, CLA2310 replaced by CLA2345)
    paper sticker AR109323
    plastic chips, CLA2345
    looks good
    JS ROMs

    Late post-Issue 6 (Thorn EMI) Datatech made QL (S/N D16-122418) with ISS.7 PCB and JS ROMs (bought on ebay in December 2001)
    D16-122418, still sealed
    ceramic CPU, plastic CLA2310
    looks good
    JS ROMs

    SAMSUNG made late American Edition (S13-004737, FCC ID: EHF 9QN QL-US-85010) with US5 PCB and JSU ROMs (bought from Phoebus in March 2002)
    S13-004737, FCC comply
    factory applied mods
    VHF channel select switch
    JSU ROMs

    SAMSUNG made early German Edition (S/N SG18-002321) with US5.3 PCB and MGG ROMs, original German Edition Power Supply with switch (Made in Switzerland)
    SG18-002321, date printed
    Power Supply for Switzerland
    standard DE-9 connectors
    This QL in action

    Brand and model name, year and ISSue number on PCB solder side (3 pics, (Thorn EMI) Datatech made ISS.5 and ISS.6, SAMSUNG made US5), my QL computer collection in March 2002 (7 QLs in a wooden box, before getting the S13-004737 and D04-001371)
    Branding PCB ISS.5
    Branding PCB ISS.6
    Branding PCB US5
    7 QLs and 3 PS in a box

    QL forever!

    Urs König (aka QLvsJAGUAR)

    Send an eMail to Urs König's "QL" mailbox (replace -at- with @).

    Site produced and copyright (c): 1999-2022, Urs König

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