[Oberon] Smallest Oberon board ever made?

[Magnus Karlsson]

Thanks!

Monochrome video framebuffer takes 96 KB (1024 x 768 / 8).
The Artix7-50 has 300 KB of BRAM, of which 128 KB is used for cache, 96 
KB used for video memory, 2 KB for boot memory and 74 KB not used at the 
moment.
The address of the video framebuffer can be changed via a register so 
that it can be moved from the default location at the end of the lower 1 
MB so above the 8 MB range.
The IPS6404 is an odd memory. Expressif, the maker of the very popular 
ESP8266 and ESP32 wireless microcontrollers also makes (or rebrands) 
this part for use with ESP32.
https://www.espressif.com/sites/default/files/documentation/esp-psram64_esp-psram64h_datasheet_en.pdf
https://www.aliexpress.com/i/4000218445956.html

Cheers,
Magnus

On 1/8/2021 3:49 PM, Pablo Cayuela wrote:
> Oh!, it's really amazing the level of integration, and even the micro 
> connectors appear big against the chips.
> If BRAM is for monochrome video memory, how much is it?
> The 128 kB caché is part of the 8 MB PSRAM chip (IPS6404) or where it 
> resides?
> The IPS6404, is it acquirable? How much is the cost? I read on the 
> IPUS site "for limited customers only", maybe you're one of them.
>
> Congratulations Magnus for such a wonderful board.
>
> Best regards,
> Prof Pablo Cayuela
> Argentina
>
>
>
> On Fri, Jan 8, 2021 at 5:04 PM Magnus Karlsson <magnus at saanlima.com 
> <mailto:magnus at saanlima.com>> wrote:
>
>     I have been playing around with a concept of an Oberon board smaller
>     than RPI zero just for fun.
>     The board is 60 x 25mm in size and runs the Oberon disk image from
>     projectOberon without modifications.
>     It has an 8 MB PSRAM chip so with software changes it supports an 8MB
>     Oberon system.
>
>     FPGA: Artix 7-50
>     KB/Mouse via PS2
>     Video via microHDMI
>     Serial/Power via microUSB
>     8 status LED
>     4 DIP switches
>     reset/abort switch
>     nRF24 RF chip with uFL antenna connector
>     8 MB PSRAM chip (IPS6404) via 128kB cache
>     Video frame buffer in BRAM (mono)
>     microSD socket
>
>     As you can see in the images below the PS2 connectors are huge
>     compared
>     to the rest!
>
>     https://www.saanlima.com/images/Oberon_zero/OZ3.jpg
>     <https://www.saanlima.com/images/Oberon_zero/OZ3.jpg>
>     https://www.saanlima.com/images/Oberon_zero/OZ1s.jpg
>     <https://www.saanlima.com/images/Oberon_zero/OZ1s.jpg>
>     https://www.saanlima.com/images/Oberon_zero/OZ2s.jpg
>     <https://www.saanlima.com/images/Oberon_zero/OZ2s.jpg>
>
>     Booting: https://www.saanlima.com/images/Oberon_zero/IMG_5862.MOV
>     <https://www.saanlima.com/images/Oberon_zero/IMG_5862.MOV>
>
>     The novel thing about this board is the use of a small QSPI PSRAM as
>     main memory.
>
>     Cheers,
>     Magnus
>
>     --
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>     list for ETH Oberon and related systems
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>     <https://lists.inf.ethz.ch/mailman/listinfo/oberon>
>
>
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