...and I'm back in 1985

Almost there, only the second (internal) hub to add, a bracket for the external hub to be made and fixed in place because servo-tape just isn't up to the job and a few other bits of tidying, such as making the HDMI socket a better fit.

Speccy Pi

My Speccy Pi is almost there, need to fit the USB stuff such as the powered 4-port hub where the edge connector used to be. I've got it working with an external keyboard at the moment but that will change once USB is sorted out, then I can have WiFi and Bluetooth as well.

I'll post some better quality pics as well as some of the inside once I get the chance to neaten the wiring up a bit.

1... 2... 8... Gosh!

Thanks to OpenSE Basic & Geoff Wearmouth's Gosh Wonderful rom, my Grey +2 is now equipped with a home toasted Gosh128 ROM - bringing together the best aspects of both projects, combined with the extra capabilities of the 128k machine. Tonight's quick test provided me with just a glimpse of what the system is now capable of and hopefully will be even better combined with a Divide when time allows.

EDIT: Maybe it's not so great after all, had some quite random behaviour from it so the ROM will be going back in the UV oven later on, time to try something else :).

EDIT AGAIN: Much of the randomness seems to have been down to the CF card adaptor I was using, it came with my other (newer) Divide so I just assumed it was going to be ok, so Gosh128 might be getting a stay of execution.

...have this

Got my new laser printer up and running, which means I can have an honest bash at making a proper PCB version of the Simple 8-bit IDE Interface for my +2e. I'm really surprised that no-one sells a kit of all the stuff you'd need to make a few PCBs at home, though admittedly - pound shop cat litter trays and salad tongs are set to play a large part here...

Take That...

Had a sort of Super Saturday of my own yesterday, I repaired 3 Speccys including one (see earlier posts) that'd been bothering me for ages. I had removed it's Z80 so I could replace it with socket in order to later fit a Simple 8Bit IDE Interface, everything went well until I powered it up and I was greeted with a red or magenta border with alternate black & white bars and flashing attributes on the screen. After hours of detective work armed only with a multimeter I found a short between D6 and A2 which could well have destroyed either TR3 because when I finally got round to replacing it with a real ZTX313, problem solved!.

Next up was an Issue 3 board I got off Fleabay that was listed with a keyboard fault, the seller reckoned it was a ULA and I had a matching but untested replacement so I thought 'Ok, I'm in...'. I replaced the ULA and tested it with known working keyboard, still nothing from the keyboard so I asked those who know on WOS Forums who suggested I replace TR6. One replacement ZTX313 later and bingo!, a working keyboard - thanks to WOSf members McLeod_Ideafix, Johan1973, RetroTechie, RoKo and Guesser for all your help.

But no... I was going for the hat-trick, an Issue 3 rubber keyboard model that I bid on before reading the description properly, untested, no membrane, knackered faceplate and no ULA!. I simply took the ULA I had just removed from the previous machine, pressed it into the socket and gritted my teeth as I powered it up. It works! - not had time to thoroughly test it yet but I have another broken rubber keyboard machine coming soon that should yield enough parts to get a working machine.

+2e

Here's inside and outside views of my +2B now that I've fitted the ROMs I burned all by myself. I was going to send off to Garry Lancaster for a pair of pre-burned ROMs but I decided that I should be brave and burn my own so I bought a pair of used 27C256 EPROMs from Ebay and a Willem 5.0e programmer from Hong Kong. To my complete surprise everything worked first time, barring a minor issue with the programmer software and once I'd gently prised out the original ROMs and wedged the newly burnt EPROMs into place I was the proud owner of a +2e.

Now all I have to do is sort out an IDE interface, I decided that I should go with the Simple 8bit Interface but if I change my mind or need to update then I have my own programmer and don't need to send my roms off to be re-burnt again. I'd just like to say a big thanks to Garry, who's hard work has provided the basis of what is proving to be a great fun project for me.

ESXDOS One Sheet Manual v0.2

I was having trouble remembering all the commands for ESXDOS, what with one thing and another going on, so I decided I'd paste all of the relevant info into a printable sheet to keep next to my Speccy. As I've got to use ESXDOS more and more, the need to fall back on FATware has decreased steadily, to the point now where I only use it for loading games via the NMI menu

I decided I would share my 'Idiot Sheet' to help other DivIDE/ESXDOS users along as they get to grips with the system and after collecting some suggestions from Velesoft have produced an updated and revised version. I can't wait for the next update of this exciting new way to use my humble Speccy and look forward to any feedback and suggestions for ways to improve this brief guide.

The ESXDOS One Sheet Manual is available here.

Do you like spheres?

(c)2009 TmK

For some reason, I find this just as amusing as I find it impressive.

DivIDE and rule...

Got my DivIDE interface, complete with 1Gb CF card from the Netherlands (thanks Ben) and almost straight away (after playing Jet Set Willy, of course) decided that I wanted the more advanced functions and read/write capability of ESXDOS, rather than the standard FATWare.

Having spent a couple of hours fiddling around with it and FATWare with the help of Velesoft's Firmware Selector menu which should help me along 'till ESXDOS matures and gains more features.

Some of the things I'd like to see implemented in ESXDOS would be some better documentation, some kind of AUTOEXEC feature and, of course LFN support.

Nope, I was doing it right...

Seems that I was doing it right all along, and that my mini-monitor just doesn't like my +2B. Someone gave me an old 20" Samsung CRT TV and the modded composite output on that is crisp with just a little ghosting but flicker free.

This is what happens when you assume things I suppose...

DSCN5864, a photo by Rick Dickinson on Flickr.

You're doing it wrong...

Looks like I went about my +2a composite mod all the wrong way - a bit of reading later and I realised that the composite signal has to come directly from the TEA2000.

I soldered a length of solid core wire to the outgoing side of D31, thinking that the diode would still afford the TEA2000 some protection with the other end going to the socket inside the modulator case. At first I tried leaving the 100uf capacitor soldered in place from my earlier exploits, this gave me a distorted but recognisable signal for the first time, the image is still 'jumpy' and there is a fair bit of ghosting in evidence, perhaps this is because I chose not to bypass/remove D31 but I'll mess about with that later.

Found my 29 year old copy of Manic Miner, dropped into 48k mode and typed the immortal 'LOAD ""' followed by Enter and pressed play...

Spectrum +2 Has Arrived

Got my +2 today, need to composite mod it before I can test it further than plugging it in and seeing the power light come on. I did it quickly but something is amiss as there is no picture, maybe something is touching the metal of the keyboard shield. I'll spend a bit more time with it when the kids have gone to bed...

The continuity continues...

Half way through checking every pin of the CPU socket for bad joints, broken tracks etc. as per the Issue 4a/b Schematic at Retroisle - no problems so far apart from the following...

Either the schematic contains 2 glaring errors so far, or my brains do. CPU Pin 2 goes pin 12 of IC3 on the schematic but is connected to pin 2 on my board, as it does in the Issue 3b Schematic. Also, pin 5 of the CPU socket is shown as connected to pin 27 of the ULA in the 4a/b schematic, same in the 3b schematic, but on my board it connects to pin 37 on the ULA like in the Issue 5 Schematic.

I'm not going to mention it elsewhere yet in case I'm wrong, or have the short from hell as a result of my dodgy soldering, or both... :).

So, 20 pins (1 to 20) later and half my optimism gone, everything is as it should be so lets hope the next 20 reveal the problem - otherwise I'm stuck.

EDIT: It also looks like I've found another error, if I am right then this is the same for the 2b, 3b and 4a schematics - pins 4 & 5 of IC24 are reversed and only seems to be correct on the Swedish Issue 3 schematic I found.

Oops...

After the desoldering of the z80 went without incident, I expected the socketed replacement to go without incident too. I soldered the socket quickly and cleanly into place, replaced the CPU and hey presto...  a choice of either red, magenta or black border with flashing attributes.

Just in case I destroyed the original CPU during the desoldering process, I had already purchased a spare and fitting this gives me additional black and white bars. The internal speaker is buzzing and nothing is getting unduly hot, I have also checked fairly thoroughly for shorts and solder bridges.

I suspect the problem is due to a poor solder joint on the top side of the board, I'll check them thoroughly before crying for help. There is no response to the reset button and sometimes the pattern changes after being left powered on for a minute or two, hopefully I haven't damaged anything else while working.

EDIT: Information regarding this specific fault is contained in the Spectrum Repair Guide, looks like I need to check each and every individual PCB track going to the socket for continuity.

Socket to me

Fired up my new temperature controlled soldering iron and carefully desoldered the z80 in my 'mod' Speccy today in preparation for it to be socketed. It wasn't too traumatic but I did sweat bucketloads while I was working away, it is the first major desoldering job I've ever tackled after all.

 


The socket I've ordered should arrive any day now and hopefully I haven't ruined the original z80 although I have a replacement one to hand just in case, then I need to start thinking about replacing the ROM with an EEPROM/EPROM - once that's all working correctly then I can order my IDE interface... 

Spot of Bad Luck

The proto board I ordered from China (no-one in the UK sells them big enough for some reason) arrived snapped in two - it's the first time I've ever had a problem with anything from the far east.

I'm f**ked off but what can you do, I think I might give in and get a new keyboard membrane after all...

EDIT: The seller concerned not only responded to my email (to my complete astonishment) but after asking for a photo of the broken board is sending a replacement :). 

Regulation Issue

Got round to replacing the regulator in my project Speccy today with a RECOM R-785.0 DC-DC Converter. I couldn't get any pics of the actual replacement in progress owing to me not having 3rd or 4th arms, but it was straightforward and mercifully free from problems.

New DC-DC Converter in place.

If anything was going to go wrong then I have a few 7805's in my spares collection, so I took a pair of snips and cropped the leads of the old regulator, having first unbolted the heatsink from the mainboard. After binning the legless 7805, I warmed the joints holding it's remains one by one with my soldering iron and pulled the legs out with a pair of pliers, then cleared the holes with the solder sucker ready for the new component. 3 solder joints later the deed was done and I wiped the sweat from my brow, grabbed my PSU and gritted my teeth - Success!

Still no keyboard though... :)

I also performed this mod that I found on Sami Vehmaa's old site, it's meant to improve video quality by fixing some ghosting issues - on my (4A) Speccy it did nothing discernable. Perhaps I might perform the other video fix on his site at a later date and see if there are any notable gains from that.

Up to speed

I'm just really rehashing/transferring the Speccy stuff on my electronics blog for something for people to read until I get up to speed and have the chance to post something interesting, in the meantime here's a picture of a Speccy.

Keyboard Kapers

I want to keep one of my Speccys boxed and as original as possible, the other one however has no PSU, box etc. and was bought without any guarantee of working, so it's fair game for a project :). I have already ordered a large piece of proto board  after being inspired by seeing a rubber keyboard Speccy with it's keyboard membrane replaced with tactile key switches, so I think it's worth a go for the £10 it 'should' cost me.

Protoboard - £3.10:

And a 100 pack of these is about £5:

I want to preserve any original parts, so we will have to see how it goes so far as the overall 'feel' of the keyboard when typing. I'd like to be able to return it original condition if needs-be, so carving up the case lid or any of the key caps/plungers is not an option.

One idea I had was to add return springs (if I can source some) to the underside of the plungers to give the keyboard a bit more tactile feedback than just the bare switches but I need to measure the distances involved more carefully first, although the biggest headache I face is placing the switches in correct alignment with each individual key's plunger.

Spec, Tech, Pain in the Neck

After many Spectrum-less years I've just found myself to be the proud owner of 2x Speccys, both 48k Plus models (no rubber keys for me) one boxed and apparently in good working order apart from the keyboard and the other untested.

When they arrived, I quickly realised that I had 2x half working Spectrums, one with a working keyboard and a horrendous video fault, and one with a dodgy keyboard that seemed to work ok. That is, until the one with the dodgy keyboard got warm after a while of being switched on - then I had 2x Spectrums with horrendous video faults...