The 512k of ram would have been sinfully luxurious back in the day when the original model came with 16k, although the most iconic spectrums would. And the spectrum lives on, with new games and hardware. Jan 07, 2015 a short video covering the diagnosis and repair of a ram fault on a rubber key 48k spectrum. It uses a machine language routine to fill an area of memory either all of upper ram or a portion of lower ram with a sequence of randomly generated values and then. In this retro teardown, we will look at the most iconic computer of british history the zx spectrum.
For details of the memory upgrade, see later on here. Special hardware, such as romantic robots multiface, was able to dump a copy of the zx spectrum ram to disktape at the press of a button, entirely circumventing the copy protection systems. How to quickly diagnose 48k ram failures, ninja style april 21, 2017 brendan hardware most of you will be used to the distinctive power on screen of the 48k spectrum, where the screen goes black with a white border, and for a fraction of a second vertical red bars can be seen, before the screen clears to the message. It was a bit thrilling i know but some words of explanation are needed. Now im back on my retro computers ive put together this quick guide for those looking to diagnose and repair zx spectrum computers. In this case, it was an issue 2 board where the colour had drifted, so i wanted to let it run for a while, and run from cold the next day to make sure it hadnt drifted again. The only interesting fact to mention is the dc bricks plug polarity while nearly anyone else tends to use barrel. Website providing useful information, including the basic code and table relating to which chip might. I bought a copy of the complete spectrum rom disassembly the spectrums os decoded and annotated, every byte of it, every bug and whistle. On spectrum pluses the fault of some keys not working, especially the keys on the bottom row. If it is found that keys go faulty when warm and the ic1 5c1126c001 ula is ok, replace the membrane. I bought an interface 1 and zx microdrive each cartridge a squiggly loop of magnetic tape in a small case able to hold a massive 85k or. Zx spectrum repairs, refurbishments and maintenance wikis.
Tynemouth software llp old computers, new computers, bespoke web design and software development, computer repairs, it and media services uk sunday, 19 february 2017 zx spectrum issue 2 repair. On reset, the spectrum should beep once and show a. Carries full assembler listings of the zx spectrum, zx80 and zx81 roms. The obsolete memories 4116 use three power supplies 5v,5v, 12v that must be applied in a particular sequence worth the integrity of the chip. The replacement ram is lower power consumption and far less likely to fail. Ql started with white screen normally it was ram fault. In the uk, the zx spectrum was one of the most popular early home computers of. The upper ram can be disabled to check if the computer then works ok as a 16k machine see indepth guide links below. The zx spectrum lower ram replacement module is a device that replaces all eight 4116s in a 48k or 16k zx spectrum it cannot be used with any of the 128k models.
The zx spectrum is supplied with either 16k or 48k of onboard ram. This clon only have one ram bank made by 4164 chip. And it also runs new software created more recently to make use of expanded hardware, including new graphics modes and faster processor speeds. A diagnostic rom image for the zx spectrum download current version.
Sep 29, 2016 in this retro teardown, we will look at the most iconic computer of british history the zx spectrum. Sinclair spectrum after the success of his two previous computers, the zx80. Games and entertainment software for the zx spectrum. February 6, 2020 phoebus dokos off happening, hero article, news, first zx spectrum next delivered today to one of our ultimate backers. Most spectrum software has been converted to current media and is available for download. Based on the compiler z88dk, the kit allows to develop games and applications in c language.
This module replace the 16kb low memory ram eight 4116 ics of the 16kb or 48kb sinclair zx spectrum. Two major modifications have been implemented on the spectrum boards. I grew up with 1980s home computers, and have been using, repairing and upgrading them for over 30 years. There was even a separate numeric keypad released for the spectrum 128, although this is normally only seen in portugal, there. The lower 16k of ram in 48k and 16k zx spectrum computers is provided by eight 4116 dram ics. With a densely populated board such as the zx spectrum, as. Zx spectrum ram paging interrupts with 128k models. Spectrum faq, 301105 since the faq is no longer maintained, for technical details you may want to see the tech info wiki. It is valid for all build standards, fitted with either 16k or 48k bytes of dynamic ram memory. If youre just getting started with your spectrum and want to test loading software from a pc or audio player, you might like to try some of the old and new games listed below. Having a set of schematics or even better a full service manual is the good thing to have before starting any repair. Sinclair zx spectrum home computer new hardware and repairs. Fault diagnosis and repair colour, repair and upgrades 36.
Using the jsmess emulator, users can boot up an emulation of the given title and use it in their browser. Apr 21, 2017 how to quickly diagnose 48k ram failures, ninja style april 21, 2017 brendan hardware most of you will be used to the distinctive power on screen of the 48k spectrum, where the screen goes black with a white border, and for a fraction of a second vertical red bars can be seen, before the screen clears to the message. This was arguably the most popular computer in british history and. Normally when you see screen corruption like that on a spectrum it is a ram fault, it is in the shared memory bank that provides both the screen. A cure without having to replace the membrane can sometimes be achieved. You can play any games, demos, use original hardware, you name it. Kind of sinclair z88 cambridge computer compatibility. Touching ram chips, the screen changes and showed a lot of colour blocks. Where a spectrum has initialised correctly but a ram memory fault is. Brendan alford the author of the zx diag software i had been using for testing confirmed the ram hypothesis and referenced an article he had written about zx spectrum ram. The vla82 is a modern plugin replacement for the spectrum 48k ula type 6c001e7 or earlier. These lists are now a bit out of date, but i have left them here for referece. The 16k version is wired so that it can be expanded to 48k by the addition of a number of appropriate plugin ics. How i did a quick and easy composite mod to my sinclair zx spectrum 48k.
The zx microdrive system was released in july 1983 and quickly became quite popular with the spectrum user base due to the low cost of the drives, however, the actual media was very expensive for software publishers to use for mass market releases by a factor of 10, compared to tape duplication. The zx spectrum was launched in april 1982, and by todays standards is a primitive machine. The zx diag cart comes with the zx spectrum diagnostics software, developed by dylan smith and brendan alford. Zx spectrum screen memory layout zx assembly for the zx. Welcome to this wiki with information about the zx spectrum, for repair, maintenance, upgrades and more.
Zx spectrum next the official portal for all things next. Timex fdd3, when power on, disk driver try to read the disk but it stops at few second. Spectrum next is an expanded and updated version of the zx spectrum, fully compatible software and hardware with the original. This one had issues with video, ram and a broken keyboard membrane. The internet archive software library is a large collection of viewable and executable software titles, ranging from commercially released products to public domain and hobbyist programs. Tynemouth software vintage computer repairs, accessories, kits.
To find the rams that are at fault we now enter a couple of program lines, no line number required. Spectrum didnt show divide screen and also nmi button didnt work. So if ic10 is faulty, then bit 4 of any byte in memory will be affected. The lil old zx spectrum 48k service manual section 4. Kodi archive and support file community software vintage software apk msdos cdrom software cdrom software library console living room software sites tucows software library shareware cdroms software capsules compilation cdrom images zx spectrum doom level cd. Other rom contents can be loaded into ram, then paged as rom. Fixing a poorly zxspectrum part 5 l break into program. I suspect ic7 and ic16 two ram chips on d1 but first, taking a tip from the lil old zx spectrum 48k. Mp3 and zipped wav audio files are provided along with a link to more information on the game at the world of spectrum web site. Also covers fixing the video out problem related to the transistor mounted incorrectly at manufacture. A short video covering the diagnosis and repair of a ram fault on a rubber key 48k spectrum. Now is the time to take the plunge and start cutting tracks. I removed all the lower bank ram chips and plugged the power supply. How to quickly diagnose 48k ram failures, ninja style.
Here is a simple program that can help in the diagnosis of ram faults in zx spectrum computers. Sinclair ql, ql started with white screen normally it was ram fault. The spectrum screen memory map is split into two sections. As they simply dont make spectrum ulas anymore, then unfortunately if the ula has failed, then options for. Feb 27, 2020 the 512k of ram would have been sinfully luxurious back in the day when the original model came with 16k, although the most iconic spectrums would be the 48k models. With a densely populated board such as the zx spectrum, as careful physical examination of the board can sometimes indicate an obvious fault. New or replacement ram for the spectrum basically comes in three types, of which you can mix two of the types. Zx spectrum, no 5v repair when repairing something like a zx spectrum, its good to run it on a soak test for a while.
This method should work the same on all older speccys pre rgb output. It started with a black screen with some vertical lines. It uses a modern sram ic and is far less likely to be damaged in the situations described above. Obviously from bidding portal and obviously i wasnt sure if it is in a working state. These tests are based on the rom based diagnostics and are intended to assist in diagnosing memory problems that may manifest themselves but where the spectrum itself is partially working for example, minor screen corruption, ability to run 16k games only etc, and. These tests are based on the rom based diagnostics and are intended to assist in diagnosing memory problems that may manifest themselves but where the spectrum itself is partially working for example, minor screen corruption. The zx spectrum uses like basically any other home computer of the time a linear regulator 7805 and some cs for smoothing the voltage to generate the 5v. We sell a wide range of new and used software and hardware to support the retro sinclair zx spectrum home computer for you to purchase. If the spectrum is 48k, an upper ram chip ic15ic22 is probably faulty. The world of spectrum faq, maintained by arjun nair. May 28, 2018 zx spectrum, no 5v repair when repairing something like a zx spectrum, its good to run it on a soak test for a while. Furthermore, the cartridges themselves acquired a reputation for unreliability, and publishers.
We have all the special parts needed in stock ulas, cpus, ram etc. This was arguably the most popular computer in british history and is wellknown worldwide. Repair and restoration of a donated rubber key sinclair zx spectrum 16k. There are more features that you can launch with a keypress directly after powering up this is shown on screen. Modifying a spectrum to take a eprom instead of a rom eprom instead of prom in zx spectrum tc2048 how to replace the rom of a zx spectrum with an eprom mark. Lower ram ics on the 48k spectrum are designated ic6 to ic, and represent bits 0 to 7 in that order each memory ic provides a single bit of each byte. A block diagram of the complete zx spectrum microcomputer is given below. Obviously, this unit has quite a past but a lot of these quickfixes are made originally by sinclair itself. December 18, 2012 arjun leave a comment go to comments. See fig 28 for spectrum and fig 38 for the spectrum plus keyboards. Zx spectrum 4 out of memory error repair tynemouth software.
If the computer is a 48k machine the 32k of expansion ram can be isolated. Sam coupe compatibile write protection of section a. If it does, you can reenable the upper ram and attempt to fault find it with basics poke and peek commands. The spectrum psu suffers mainly from the wires in the premoulded plug or lead exit from the box snapping or going intermittent. You see that on commodore pets and c64s with ram faults, but i have never seen it on a spectrum before. Over the many years that i have been writing spectrum software a number of habits have formed which may seem odd. Repair and refurbishment service for your rubberkey zx. Zx spectrum 128 ram testeralso works with 16k and 48k spectrums. If no fault has been found and the computer still has not initialised, the fault could lie in the ram.
L break into program zx spectrum screen memory layout. We have 3 sinclair zx spectrum manuals available for free pdf. Whether you want to just get a faulty spectrum back up and running, or need a ula replacement for a new clone, then the vla82 is. Zx spectrum issue 2 repair and restoration youtube. For smaller parts ram chips and the like we have no charge, and for the major parts except the ula we charge. Apr 23, 2012 i bought a copy of the complete spectrum rom disassembly the spectrums os decoded and annotated, every byte of it, every bug and whistle. Tested with an extensive suite of zx spectrum software. Probably clive sinclairs most successful and famous invention is the zx spectrum. Ideal for installing in an aftermarket spectrum pcb without needing an original ula. Zxtunes it is worlds biggest zx spectrum 8bit music collection. It is common for these to fail through simple old age or due to other faults in the computer, in particular failure of the circuit that generates the multiple power supply voltages needed by the 4116s. Nov 01, 2019 now im back on my retro computers ive put together this quick guide for those looking to diagnose and repair zx spectrum computers.
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