[this has been written over a few days, so there maybe some disconnects here and there]
I just bought this very same Turbo King from eBay as mentioned and pointed out in another post on the forum and it got delivered Tuesday! In the end, I paid £89 plus delivery which I don't think is a bad price considering its condition and collectability. By the way, I've read all the forum posts here pertaining to this device and what people have said regarding upgrades, repairs and expansion.
I thought I'd share my experiences with it so far in the hope of providing more information that I either couldn't find here, or elsewhere on the Internet.
As you may have surmised: I've already taken off the back cover to have a look at the condition of the internals and also see what software it is running. The board is in perfect condition with no signs of oxidisation I’m also intend burning 3 versions of EGR EPROMS to try out.
What did I buy? The unit contains a Rev.2 motherboard (photos of this can be found on the Internet) It has gold plated through holes and vias on the PCB. The build quality, in my opinion, is exceptional and doing a comparison between Rev.1 and this board shows a step-up in design and production quality like better flex connectors for example. Included was the original 1987 manual, but this unit was manufacture after January 1989 according to the latest date code on the ICs. The serial number is 210763, that maybe a high number, but we wouldn't have known what the initial/starting production number was, so it's just a point of reference. The manual contained a Guarantee Registration card that had been filled out by the original owner i.e., name, address and that he purchased it from Harrods in London.
Components used? This board has a 65C02P-6 CMOS variant CPU installed. The 6 pertains to the operation speed of 6MHz, however, there is only a 5MHz quartz crystal installed. As you may have seen, the Rev.1 boards use a P-4 4MHz CPU, but utilise a 5MHz crystal, so there is a 1MHz overclock in play. There are many differences between the Rev.1 and Rev.2 motherboards and 'anomalies' that I haven't seen mentioned in other discussions. The main differences are: Rev.2 board doesn't contain a second static RAM chip in U7 as does Rev.1. This RAM chip is a Mitsubishi M5M5165P-12L (12L pertains to 12ms access time of the device) It has a 65,536-bit capacity, or 8,192KB of RAM. The RAM is a low power Static CMOS design that can retain its contents consuming very little power.
16KB of RAM? The Rev.1 board has two of these chips populating the board meaning a total of 16,384KB of RAM. Some of you will remember that the decal on the front of the machine states: 2150 Elo Strength, 80K (expandable to 144KB) and User Programmable Library as key features of the device. Note the stated 80K as standard and the 16KB RAM mentioned in the manual that doesn't seem to have ever been updated other than an addendum. If the Rev.2 board doesn't contain the additional 8,192KB chip then it's not got 16,384KB of RAM!
Where does the 80K come from? So, the Rev.2 board has 8KB of RAM and 2 x 32KB EPROMs (excluding the EGR) = 72KB of total memory and NOT 80K.
Does the Rev.2 custom Saitek HELIOS ASIC (68 pin SDIP Shrink DIP) contain the additional 8KB missing from the omitted chip in U7 on the PCB? Perhaps they updated the Saitek custom chip to contain more RAM and save on the extra production costs? We will never know as I've been unable to find a datasheet for the device because it was proprietary although manufactured in partnership with NEC.
There is a document from www.schaakcomputers.nl that mentions the chip, but only of its introduction and some details of what it does, but nothing on further/future updates, [sic] "there will also be additional benefits to playing strength. The main processor has less bother with menial tasks such as scanning the sensor board, lighting LEDs, sounding beeps, keeping clock times, and the myriads of other things a chess computer must do. Helios looks after all that. So, the main processor can spend its time doing what it is really good at: playing chess."
Installed EPROMS and Versions? The Rev.2 contains 2 of the same type of EPROMS M27C256-(type/speed rating) that are UV erasable and 12.5v programmable devices with a capacity of 32,768KB. Versions installed in my Rev.2 board: EPROM 1: W1/YO1F 728P U3 EPROM 2: YO1F/B 8190 U4. There is a moveable jumper labelled 'JA' between U4 and U5 (where the EGR goes) that is set to disabled. Looking at the PCB traces, when enabled it appears to enable the currently empty RAM space U7. There are, however, 3 separate unpopulated jumpers in between U5 and U7 and one other between the CPU and U3. I am assuming the reason this is configurable, is that they were designing more RAM into an updated HELIOS chip. Otherwise, this would be pointless.
How do I get an EGR chip for my unit or upgrade the system firmware? Well, you need an M27C256 EPROM, a programmer and the files to 'burn' on them. But, where do I get the required files? This took me a while, but they are available in the CB-EMU Pro installation folder. "CB-Emu_Pro (Chess Computer Emulator) (final version!) Emulator for about 400 retro and vintage chess computer versions (based on MAME/MESSUI) (includes now MessChess for usage in any UCI/WB-GUI)" Available from: https://fhub.jimdofree.com - Once installed, go to the \\CB-Emu\MessExtra\roms folder and look for the .zip files: tking.zip, tkinga.zip. tkingb.zip and tkingx.zip - these contain the system firmware for the U3 and U4 EPROMS. To get the EGR EPROM files, look in the same folder for the files: egr.zip (EGR I), egr1.zip (EGR I upgraded) and egr2.zip (EGR II - egrii_707_u4). These zip archives contain .bin files you can use with your programmer to 'burn' the software onto your EPROMS.
What if I try to use different EPROM versions with my Turbo King I; will it break it? No, if the system code in the EPROMS is not compatible, then the system just won't boot or function correctly. Regarding the EGR EPROM versions, they will either be picked-up and work, not be picked-up or the system won't boot. Just revert back to the originals or try another version.
I don't have a programmer or UV eraser or the EPROMS - Is it worth it? - Considering the chances of picking up any original EPROMS in various versions is next to zero, you can buy a programmer from AliExpress for around £40, a pack of 10 or 20 EPROMS from eBay or AliExpress for £10-£20 and a cheap UV eraser for about £20 from the same places.
The onboard regulated 5v power supply? Instead of using an off-the-shelf 7805 voltage regulator chip (5v) that even the original Fidelity Chess Challenger 10 from 1978 used, they opted to design one using 3 power transistors with diode clamping. It's complicated, very elegant and well designed. However, the number of components and board space beggars’ belief although I do appreciate it; despite it having a higher chance of failure due to the number of components used. The DC adaptor input even has inductors on the plus and minus lines as well as the one to the switch used to select either battery or DC power inside the barrel jack. There is also an inline choke coil across the plus and minus DC input to reduce spikes and inhibit noise on the PCB!
The LCD display board has its own 32,768Hz quart clock crystal. This must be because it keeps the times independently. So, answering the question, “does an overclock affect the clocks” – it doesn’t look like it, but I may be wrong?
The system clock @ 5MHz is tied directly to the HELIOS ASIC which is micro controller that controls the on board 65C02 CPU’s clock speed and other accesses including ROM and RAM. Overclocking this would affect this device directly, but would also indirectly affect the speed of the 65C02. However, since this ASIC is microcontroller, its settings like that 65C02 CPU multiplier/divider are most certainly controlled through this chip. These settings would not be in an onboard masked ROM, but loaded from the first system EPROM. So, overclocking the system without changing variables in the EPROM would cause a problem. I don’t know as I haven’t tried yet.
Finally, I’ve burned all three available EGRs to EPROMS and booted the system with them installed. The system boots and ‘seems’ to work normally. However, I have no idea whether these EPROMS are being detected or even used? Does anybody know how to check whether they are working. Does anybody have a manual for the EGRs that contains further information that may help? Is there a combination of keys that bring-up a service menu?
As yet, I haven't burned any of the system ROMs and tried them. I do have the option to burn a D++ EPROM, but not sure if this will work at all. Does anybody know?
Many thanks in advance for any and all suggestions you have that may help me in my endeavours!
Andy