I have never needed to suffer a situation where power was only available for an hour every day.

But I did start out way before WWW was invented. I remember when I got to load a 1200 baud modem, and how I had to plan what I wanted to do when connecting to the university, since the phone costs couldn't be ignored.

I think that you should maybe read my post once more, and think about what I wrote. If someone wants help, it really is important that they know about, and think about, how a forum works, and what psychological factors that affects the progress of a request.

What little feedback there has been in this thread has shown that a circular buffer is a too large step to take. In my view, the most reasonable smaller step to look at would then be to focus on the actual output code, i.e. ignore fonts or scroll or anything like that and just concentrate on how to emit existing bitmap data at a reasonably high speed. This is a required step that must be taken whatever algorithm that is used for deciding what do display. And it can be performed with a hand-created little bitmap of a single character (possibly duplicated a couple of times) with the only intention that the visible pattern on the 8x8 will confirm that the output code works.

But the thread is currently stuck there. The OP isn't interested in subdividing the problem into smaller sections (maybe for not understanding the value of subdivision of too complex problems). And no one have managed to come up with any other suggestion of a suitable small problem to focus on. In the end, this has just resulted in a thread in dead-lock. When something is in a deadlock state, you have to try to push it in some direction and see if you can get things starting again. The OP did a push - asking for someone to rewrite the code. I did my push, suggesting that the OP should read what has been written in this thread and then come back with more questions or explanations why he avoids the suggestions that have been made.

The final point is that the OP will be much more successful in getting help if he does the reverse of what you suggest. In this case thinks about the people who do help on forums, and what people may have for reasons to help. This is a two-way street. The people who help must try to visualize the problems in a similar way that the person who needs help sees them. But the person who requests help must not take help for granted, and must not think that it is enough to post a request and then dozens of suggestions will come in until the suggestions may be combined into a turn-key solution. The requester must spend more time giving information to direct the help in the correct direction and show that given help is looked at.

Everyone who have spent some time on forums notices that in some threads, people can receive almost infinite amounts of help. The problems may be trivial from a professional developers point-of-view, but there are no comments abut the complexity of the problem, and no remarks even if the same solution is described five times in different wordings with or without graphical help. People help because they get a feeling that the help is meaningful. At the same time, there are every day new threads that almost immediately ends up in a deadlock. Either no answers, or someone throwing in a RTFM or similar. It is important for both requesters and helpers to notice these things and think about why they happen. A helper with a bit of experience can be a bit more forgiving, but a forgiving attitude can't help in a thread where there is no feedback. A requester can avoid initial problems by starting to focus on describing the problem directly in the first thread, and in the description also include the reasoning behind any made decisions. And the requester can avoid thread stalls by showing that he/she is following the thread, and still interested.

Some forums may have a FAQ link about "How to get help on this forum". But in the end, when a thread stalls because of too little feedback you have two choices. Ignore the OP or ask them to activate themselves and start showing that they are a part of the solution, and not a part of the problem. I don't see this as disrespecting the OP or ignoring the social or economical situation the OP may be in.