You were lucky to get one that worked - they seemed to have a rather high failure rate and were also a bit of a pig to work on because there are 3 PCBs connected together with fragile paper flex cables inside that rather small case. Also, if you have the original Grundy PSU then it's advisable to take it apart and check to see if it has those plastic encapsulated Rifa caps in it, since they have a habit of cracking, letting moisture in then blowing up while generating clouds of foul smelling smoke.
@@CDESP072 I think it's worth taking a look though - that cap is located underneath the power transformer and I had no idea it was even there until it blew up. If you see cracking in the plastic housing then consider replacing it. IRRC, the one in the Newbrain is one of those 3 caps in one package thing - it has an X cap across the line and neutral and a pair of Y caps going between live/neutral and earth. In my case, it was the X cap that blew up.
Woow, something off with the screen there. Cool, It seems like Chris Wittington, did some of those games, since Memotech MTX have a version of Draughts/Checkers by him also, man I played that games so much and got very good at Checkers playing my Memotech :) fun times.
The newbrain was the very first computer I worked on in the early eighties. Still have good memories off it. I hope it can and will be ported to the mister fpga platform.
It is an interesting project. can briefly explain how vram is "seen" from the cpu perspective? is seen as a memory paged block, is shared in the z80 space? Do the CPU be slowed down or blocked when it does access the vram during screen build up ? ( i think no, because of dual ported ram)
I have my own assembler/disassembler that can put programs directly to the z80 RAM through rs232 or can dump these programs to disk to be burned on eprom or used otherwise.
The LCD 800x480 screen has its own memory 1.2MB. You first send a command that sets a rectangular area on the screen like 200,200,300,300 and then using an out you send the color of each pixel, in the previous example 100x100=10000 pixels but i need to send two bytes cause i am using 18 bits for color information, so two out commands. This mode is selected because its the only one i could use with my 8 bit data bus so the 9th bit its just a copy of d7. All other modes need either more data bits or 3 bytes per pixel. Now for the text all is done by the Z80, i have the character bitmaps in rom and i use that to display text on lcd which is bitmap only.
Grundy NewBrain old Retro 8 Bit Z80 Computer : Type Emphasis: Education, Portable computing, Programming, Small business Release date 1982; 39 years ago Introductory price Model AD 229.00 GBP, Model A 199.00 GBP (United Kingdom, 1982), 48,000.00 GRD (Greece, 1985) System on a chip Keyboard and one-line VF display chip: COP420 MCU CPU 8 bits Zilog Z80A @ 4 MHz Memory 32 KiB RAM (Maximum 2 MiB) 24 KiB ROM Display Text modes: 32×25, 32×30, 40×25, 40×30, 64×25, 64×30, 80×25, 80×30 Graphics Composite video, UHF TV output Graphics modes: 256×256, 320×256, 512×256, 640×256 Total number of colours: 2 Input 62 keys I/O Ports:2× Tape recorder (1,200 Baud), Expansion, 2x RS-232 (to 19,000 Baud)
Hi i would really appreciate if could you please share the code the gy521 gyro? the relevant reading and converting the values to angles will do. thanks a lot :)
Wow ... I can see you've put a lot of man-hours into this homebrew Z80 computer. It Will be great to see when it's finished.. Are you planning on putting into a PCB ?
There are a number of small PCBs that you should make and connect to each other. Check this as it has all the neccessary file and info you ll need. github.com/cdesp/Newbrain-Laptop
Hi. Great Project.. I remember the Grundy Newbrain in Magazines I read in the 80s... Sadly it was never very popular ! Are you going to design a Single board Computer of this design ?? That would be Cool !
Would it be possible to make a 'Mini' NewBrain like : Z80 CPU 32K D/PortSRAM (IDT7007 etc) 128K/512K SRAM 32K EPROM EPM9320 (instead of EPM7160) EPM7128SLC84 MCU for other I/O stuff
I did that as you can see. The idt7007 is a little bit difficult to find at a nice price so i upgraded my project to use a Cyclone IV FPGA and i use special chips to convert from 5v to 3.3v.
I was getting ICs at these sort of prices: Z80 (LH0080B ,Z84C000xPEC) $1.0 each 128K SRAM $1.0 each Eproms $1.0 each IDT7007 PLCC $12.50 each EPM9320LC84 $20 each (though the EPM9320ALC84 are better) CY7C341B-25 PLCC $5.0 each EPM7128SLC84 PLCC84 $2.0 each Z80 KIO PLCC $2.0 each (optional) Other ICs and bits and bobs should be quite cheap (says me!) ?? So It should be possible to make one for under £100 ??
Hi. This is a highly interesting project.. as the Grundy NEWBRAIN was never really that popular...... when do you think it will be finished, so we can see it in it's entirety ? Thanks for showing the video, I hope you make more.
+Harry62811 Check this ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-Uvrsb35XG70.html The project is complete meaning it works ok and i have just uploaded everything on GITHUB here github.com/cdesp/Newbrain-Laptop
