USB keyboard controllers
Can you make a USB keyboard adapter for (insert name of computer here)?
- Yes, I have already converted many of them - see here. If yours is not on that list, then I would probably need you to send me the keyboard to allow it to be converted
- No, sorry, mine are all USB
- Sorry, it won't, those are passive adapters for keyboards which support both USB and PS/2 protocols.
- Oh dear.
- No, sorry, mine work the other way around, and allow you to use a broken (name of computer) as a USB keyboard.
- Most keyboard controllers I make are designed for use with a modern desktop operating system. As such, the keys are mapped so that when you press a key, the symbol on the key will appear on the screen. This is complicated by the fact they are often on different keys i.e. close brackets is usually shift + 0 on a modern PC, but shift + 9 on an old computer, so when you press the close brackets combination shift + 9 on your old key board, I need to send shift + 0 to the PC so that it will display the right thing. This is also complicated by the USB protocol being written in terms of the US keyboard, so I often need to convert multiple times for each key.
- Some keyboards (e.g. C64 or Spectrum) come with an option for emulator support. In these modes, each key will only send a single key on a modern keyboard, there is no remapping for symbols on different keys. This suits emulators where they use a positional mapping (such as vice positional mapping), so you press CTRL (the key to the left of Q on a C64), the controller sends TAB (the key to the left of Q on a PC keyboard), and vice converts this back to CTRL. This gives a 1:1 mapping , so all keys and key combinations should work directly.
- If not supported directly on your emulator, you can use the following command on a Raspberry Pi
- echo mmc0 > /sys/class/leds/input0\:\:numlock/trigger
- If there is nothing connected to it, then it does not do anything. It is reserved for further development.
What's the difference between a Minstrel 2 and 3?
- The Minstrel 2 follows closely the ZX80 design, so is very much ZX80 compatible, but with extra RAM and some improvement on the video output. It supports the original ZX80 4K Integer BASIC and the ZX81 upgrade 8K floating point BASIC, but does not support ZX81 NMI slow mode, so most games will not run
- The Minstrel 3 is a new machine designed to be ZX81 compatible, including NMI slow mode, 32K RAM high resolution graphics support and much improved video output.
- The Minstrel 3 is fully ZX81 compatible, the Minstrel 2 isn't quite (it supports ZX81 BASIC, but not slow mode, so most games will not work).
- The Minstrel 2 comes with 16K of RAM, the Minstrel 3 has 32K
- Yes, there is a jumper to select PAL (50Hz) or NTSC (60Hz) framerate
- Yes, the Minstrel is designed to fit in a ZX81 case
- Sort of, there are two holes in the case moulding for the video jack, you would need to open up the other one which is normally closed on a TS1000.
- No the Minstrel is ZX81 shaped, which is smaller than the ZX80, and the connectors are in different places
- Now this is just getting silly.
- Yes, it will work with a ZXpand or ZXpand+, but also has it's own dedicated Minstrel ZXpand.
- No, the Minstrel ZXpand is designed to work with the Minstrel only, so does not contain the RAM or ROM required to work with an unmodified ZX81.
- Yes, I am sure it will not work. I'll probably have to do a blog post proving that at some point.
- Yes, I expect so. I have not tested every title, but all the ZX81 software I have tried so far has worked (with two exceptions, both from Paul Farrow). ATE does not work, but he has supplied a version which does - ATEZXP. Celebration also does not work, but there is no replacement. (Paul's website appears to be down at the moment).
- Possibly. I have tried to give as much support as I can. Some titles (such as those from Revival Studios) support the ZXpand joystick interface. Some (usually BASIC games) use the INKEY$ method, and some (including Paul Farrow's ZX80 flicker free games) use the Kempston interface.
- Possibly, I have not tested many ZX81 expansions. Some may have issues due to the extra RAM in the ZX81 memory map, others should work OK.
- Yes if it plugs into the 5x8 way keyboard connector.
- Probably not if it is connected via the edge connector, it may not work if you have built your Minstrel using HC logic chips. Ones built with LS chips should work with external keyboards. The original designed relied on the way LS TTL chips have strong pull down but weak pull ups, so the onboard chip could be driving high (weakly) and be overriden by the external keyboard driving low (strongly). This does not work with the equally matched totem pole outputs of CMOS chips. To remedy this would required additional ICs or diodes. One solution is to replace IC24 and IC25 with 74LS257s. These only drive the Z80 databus, so it should not cause other problems.
- It's up to you. I prefer the tactile switch keyboard withoverlay PCBs, as this is the better typing feel and has all the keywords and symbols visible. The ZX81 membrane is closer to the original, but is just as unresponsive.
- Not really, the current draw with the Minstrel 3 (even with Minstrel ZXpand and SD card) is well under 100mA, so with a 5V supply, the regulator is burning less than half a watt, so it doesn't need one.
- Yes, LS TTL chips are supported on the Minstrel 3 and recommended on the Minstrel 2.
- Yes, on the Minstrel 3, but not the Minstrel 2
- I redesigned most of the circuits that were dependent on the more analogue properties of the chips in the Minstrel 3, so it is now possible to use all CMOS chips.
- They are fine if the whole system is CMOS, but can cause lots of issues if mixed with the LS series TTL normally used in these sort of machines, so I generally do not recommend them when used as part of an existing system.
- These should work on both the Minstrel 2 and 3, but some tweaking may be required. I would recommend LS on a Minstrel 2 and HC on a Minstrel 3.
- No, you need to stick of LS or HC, if you mix them you will have problems
- Not really, too much has changed, the only thing in common now are the three big chips, the ROM, the RAM and the Z80.
I bought a Minstrel 2 and it flickers every time I press a key
- Yes, it's meant to do that. It's a ZX80 clone. The ZX80 does that, so the Minstrel 2 has to. (see How the ZX80 works for more information as to why).
I bought a Minstrel PCB from a Russian seller on ebay and it doesn't work
- Good luck with that. It's a board recreated from photographs and supplied with the wrong chips. If you want a Minstrel PCB, please get one from my Tindie store, or TFW8b.com or SellMyRetro. Please do not support the guys on ebay who seem to search around the net for PCB designs they can copy but give nothing back.
Will the PET ROM/RAM board fix my PET?
- Probably, many faults of PETs are caused by faulty RAM or ROM, particularly on the early 2001 series PETs with 6540 and 6550 chips.
- No, there could be other problems, but it is usually a good start
- No, these are hard wired into the video circuit, and cannot be replaced from the CPU socket. If you see random characters that change with a power cycle, these are probably OK.
- No, I don't think so. The PET ROM/RAM only expects a 6502 CPU to be installed in it's socket, so does not monitor the 'No_ROM' signal that the Super PET 6809 board uses to disable onboard ROMs. It will work in 8032 mode, but not 6809.
- Electrically it should, but mechanically it may be a problem. The PET ROM/RAM needs to remain plugged into the PET board, and cannot be plugged into the 64K RAM board. However, as far as I am aware there is very little software that can make use of the extra RAM. BASIC will only ever register 32K, the extra RAM can only be used by software designed to use it (which is Zork and a German OS). Unless you specifically need it, you would be best to disconnect it and go back to an 8032.
- PET Test is a simple ROM for the PET which is executed by the 6502 in the PET in place of the KERNAL ROM. It tests the first 1K of RAM and displays the results on the screen as G(ood) or B(ad) characters. It then alternates with a character set display to test video RAM. This does not support later PETs with 6545 CRTCs, unless you boot to one of those to initialise the CRTC then switch to the PET Tester.
- PET Diagnostics is something with replaces the 6502 in it's socket and uses a microcontroller to exercise the PET busses and test ROM and RAM and displays the results on the screen.
- No, that hardware works with the PET because of it's fairly isolated video circuits. The other systems I tried need more horsepower to drive than the microcontroller on there is capable of
- No, these have been discontinued, please see the SD2PET future instead.
- Yes, if it has BASIC 2 or BASIC 4 and an IEEE-488 edge connector and datasette edge connector. This means it will not work with the 8xxx-SK series as these have different IEEE-488 connectors.
- No, the SD2PET is designed to plug directly into the PET as the only IEEE-488 device.
Where can I buy your stuff?
- Most of the things I make can be ordered from my Tindie store. All the blog posts have links in them to order the specific items. You did see the links, didn't you?
- I designed products for TFW8b. They sell some of my things on their store. I sell some of their things on my Tindie store. You may be better ordering from one store or the other if you want a variety of products or postage options. You can normally get more options for my products from my store and vice versa.
- No, TFW8b does sell Minstrel boards on ebay for me, but I don't.
- The Tindie store defaults to dollars, but once you log in, it will display the price in your local currency. All products are designed, built, tested and shipped from the UK.
- You can contact me direct if you wish to pay by PayPal or UK bank transfer instead.
- I use Royal Mail international postage. They quote "Europe delivery aim: 3-5 working days, Worldwide delivery aim: 6-7 working days". I recommend tracked and signed option in countries where we have had problems with parcels going missing (such as Italy and Brazil) or delays in customs (such as the US and Canada), or for any orders for higher value items.
- Please check the tracking. If you didn't select tracking, then keep looking out of the Window. After a couple of weeks, it is also work checking your local post office as there have been many occasions where items have been waiting there and no card has been left with the recipient.
- Probably not, but if I do, there will be a blog post about it
- They take too long to make all the different options
- There was too much variation in the timing of different machines that I couldn't guarantee it would run on all machines. The design relies on consistent timing, and the timing is controlled by some inductors and capacitors in a 400, so it varies too much so I decided it was best to give up on these.
Have you not got just one left? [implied: just for me, because I am special]
- No, sorry. If I did, I would probably have it listed as in stock. The reason (insert name of desired item) is not in stock is that I don't have any left. Thanks to persistent folk, I don't have any examples left of some things I used to sell and got badgered about when I stopped making them. I don't like disappointing people, but if I have not got any left, then I've not got any left. If I'm not making any more, then please accept it is for a good reason.
Can you repair my (insert name of computer here)
- Probably, but I don't get much time these days, so if you are in a hurry, best look elsewhere
- No, (see above), if there had been, I would have told you about it. These sort of questions don't really help, when I am already working all hours, seven days a week. Generally after a couple of these messages I box up unrepaired machines and return them. Sorry.
- No, sorry, just because you bought it cheap doesn't mean the repair will cost any less
- Sorry, due to the extra work required, I try to avoid working on boards that have already been 'got at'.
- I am delighted to say I am no longer working on modern computers, so I'm afraid I cannot help you.
- No, sorry, I don't believe in recapping (see link to blog posts where I complain about this modern trend of unnecessarily recapping everything).
- No, sorry, I have yet to be convinced this is a wise move. It seems to be bleaching the plastic rather than restoring it, and seems to make it more brittle and more susceptible to going yellow again quite soon. Better just clean it properly.
- You could say that.
Where can I keep up to date with your work?
Are you on facebook / myspace / bebo / world of cat gifs?
I think your blog posts are great, how can I support you?